This question may be very simple for most of you, but everyone in my study group got different answers please help!!
Simplify:
28 - 9 and 21/35
I got 9 and 3/5 as my answer.
For this one: 28 - 9
If the problem was 28 - 8, would you agree with me that the answer would be 20? So now if I take one more away, that is 28 - 9, I should have 19 right?
When simplifying ones like 21/35, see if you can see a common factor in the numerator and denominator. I see a 7 (maybe there are more, but we can deal with them one at a time), that is,
$\displaystyle \frac{21}{35} = \frac{7 \times 3}{7 \times 5}.$
Now, you should be able to convince yourself that 7/7 = 1. So our fraction becomes
$\displaystyle \frac{7 \times 3}{7 \times 5} = 1 \times \frac{3}{5} = \frac{3}{5}.$
So your second answer looks good. As an additional note, since 3 and 5 are both prime numbers, we can instantly say this can not be simplified any further.
Hope that helps.
if the problem is $\displaystyle 28 - 9 \frac {21}{35}$
then you are correct. the answer is $\displaystyle 18 \frac 25$ or, as i would prefer to write, $\displaystyle \frac {92}5$, but for some reason, writing improper fractions is a sin at this level, i think they are neater