# Thread: Need help with some pre Algebra

1. ## Need help with some pre Algebra

Hello Math Help.

as the title says, i need help with some problems. Math has never been my strong suit, i have a test Monday and I'd like to figure out how to solve these problems thanks for your help.

for the first one answer i got 6 and my calculator gets 57

Operation with integers

1 54-6÷2+6=?
my work
54-6÷2+6
48÷2+6
48÷8
6 what am i doing wrong?

Operation with fractions

3 if (3/4-2/3)+(1/2+1/3) is calculated and the answer reduced to simplest term, what is the denominator of the resulting fraction?
my work3/4

4 1/2(2/3÷3/4)-(4/5x5/6)=?

exponents

8 saying 4 < öx < 9 is equivalent to saying what about x?

ratios and proportions

10 if the total cost of x appes is b cents, what is a general formula for the cost, in cents, of y apples?

12) 12) This year. 75% of the graduating class of harriet tubman high school had taken at least 8 math courses. of the remaining class members, 60% had taken 6 or 7 math courses. what percent of the graduating class had taken fewer then 6 math courses

please show work so i can understand and thank you for your help.

2. Originally Posted by grandking3
Hello Math Help.

as the title says, i need help with some problems. Math has never been my strong suit, i have a test Monday and I'd like to figure out how to solve these problems thanks for your help.

for the first one answer i got 6 and my calculator gets 57

Operation with integers

1 54-6÷2+6=?
my work
54-6÷2+6
48÷2+6
48÷8
6 what am i doing wrong?

Operation with fractions

3 if (3/4-2/3)+(1/2+1/3) is calculated and the answer reduced to simplest term, what is the denominator of the resulting fraction?
my work3/4

4 1/2(2/3÷3/4)-(4/5x5/6)=?

exponents

8 saying 4 < öx < 9 is equivalent to saying what about x?

ratios and proportions

10 if the total cost of x appes is b cents, what is a general formula for the cost, in cents, of y apples?

12) 12) This year. 75% of the graduating class of harriet tubman high school had taken at least 8 math courses. of the remaining class members, 60% had taken 6 or 7 math courses. what percent of the graduating class had taken fewer then 6 math courses

please show work so i can understand and thank you for your help.
1. You need to use the Order of Operations (i.e. BODMAS).

Do anything in BRACKETS first,

then ORDERS (i.e. POWERS)

then DIVISONS and MULTIPLICATIONS

then ADDITIONS and SUBTRACTIONS.

So $\displaystyle 54 - 6 \div 2 + 6$ you have to do the division first...

$\displaystyle = 54 - 3 + 6$ and then the addition and subtraction left to right...

$\displaystyle = 51 + 6$

$\displaystyle = 57$.

3. You need to find the lowest common denominator.

$\displaystyle \left(\frac{3}{4} - \frac{2}{3}\right) + \left(\frac{1}{2} + \frac{1}{3}\right)$

The lowest common denominator is 12, since it is the smallest number that 2, 3 and 4 all go into.

4. $\displaystyle \frac{1}{2}\left(\frac{2}{3} \div \frac{3}{4}\right) - \left(\frac{4}{5}\times\frac{5}{6}\right)$

You need to use BODMAS, so do everything in brackets first.
To divide fractions you use "stay, change, flip". In other words, keep the first fraction the same, change the divide to a times, and flip the second.

$\displaystyle = \frac{1}{2}\left(\frac{2}{3} \times \frac{4}{3}\right) - \left(\frac{4}{5}\times\frac{5}{6}\right)$.

Then to multiply fractions, look for anything that cancels, then times tops and times bottoms.

$\displaystyle = \frac{1}{2}\left(\frac{8}{9}\right) - \frac{2}{3}$

$\displaystyle = \frac{4}{9} - \frac{2}{3}$

$\displaystyle = \frac{4}{9} - \frac{6}{9}$

$\displaystyle = -\frac{2}{9}$.

3. Originally Posted by grandking3
Hello Math Help.

as the title says, i need help with some problems. Math has never been my strong suit, i have a test Monday and I'd like to figure out how to solve these problems thanks for your help.

for the first one answer i got 6 and my calculator gets 57

Operation with integers

1 54-6÷2+6=?
my work
54-6÷2+6
48÷2+6
48÷8
6 what am i doing wrong?

Operation with fractions

3 if (3/4-2/3)+(1/2+1/3) is calculated and the answer reduced to simplest term, what is the denominator of the resulting fraction?
my work3/4

4 1/2(2/3÷3/4)-(4/5x5/6)=?

exponents

8 saying 4 < öx < 9 is equivalent to saying what about x?

ratios and proportions

10 if the total cost of x appes is b cents, what is a general formula for the cost, in cents, of y apples?

12) 12) This year. 75% of the graduating class of harriet tubman high school had taken at least 8 math courses. of the remaining class members, 60% had taken 6 or 7 math courses. what percent of the graduating class had taken fewer then 6 math courses

please show work so i can understand and thank you for your help.
8. $\displaystyle 4 < x < 9$ says that $\displaystyle x$ lies somewhere in between 4 and 9, but is not 4 or 9.

10. This is a ratios problem...

$\displaystyle x : b$

$\displaystyle 1 : \frac{b}{x}$

$\displaystyle y : \frac{b}{x} \times y$

So the cost of $\displaystyle y$ apples is $\displaystyle \frac{b}{x}\times y$.

12. $\displaystyle 75\%$ of the graduating class did at least 8 maths courses.

$\displaystyle 60\%$ of the REMAINING $\displaystyle 25\%$ did 6 or 7.

So $\displaystyle \frac{60}{100}\times\frac{25}{100} = \frac{3}{5} \times \frac{1}{4}$

$\displaystyle = \frac{3}{20}$

$\displaystyle = \frac{15}{100}$

$\displaystyle = 15\%$.

So of the graduating class, $\displaystyle 15\%$ did 6 or 7 maths classes.

So the remainder did less than 6 classes.

This remainder is $\displaystyle 100\% - 75\% - 15\% = 10\%$.

So $\displaystyle 10\%$ of the class did less than 6 maths classes.