# Thread: Algebra. Trying to learn and need help.

1. ## Algebra. Trying to learn and need help.

Tom is 12 years older then sonny. In five years will Tom be twice his age then what Sonny was 4 years ago.

How old are they?

Thanksnfor the help if ther is any 😅😘

2. ## Re: Algebra. Trying to learn and need help.

Let's use letters. For Tom, we will use T. For Sonny, we will use S. The word is means equals. Older than means plus.
$\displaystyle \begin{matrix}\text{Tom} & \text{is} & 12\text{ years} & \text{older than} & \text{Sonny} \\ T & = & 12 & + & S\end{matrix}$

$\displaystyle \begin{matrix}\text{In five years will} & \text{Tom} & \text{be} & \text{twice} & \text{the age than what} & \text{Sonny was 4 years ago} \\ \text{(5 +} & T\text{)} & = & 2\times & ( & S-4\text{)}\end{matrix}$

This gives two equations:
$\displaystyle T=12+S$
$\displaystyle (5+T) = 2(S-4)$

Do you know how to solve a system of two equations?

3. ## Re: Algebra. Trying to learn and need help.

No, this is new to me.

4. ## Re: Algebra. Trying to learn and need help.

Is this a problem given to you by your math teacher?

5. ## Re: Algebra. Trying to learn and need help.

This is a task from a math book for "High School". Im studing on my own until i start school agine. Soo no, a teacher did not give me this math problem

6. ## Re: Algebra. Trying to learn and need help.

Originally Posted by SlipEternal
Let's use letters. For Tom, we will use T. For Sonny, we will use S. The word is means equals. Older than means plus.
$\displaystyle \begin{matrix}\text{Tom} & \text{is} & 12\text{ years} & \text{older than} & \text{Sonny} \\ T & = & 12 & + & S\end{matrix}$

$\displaystyle \begin{matrix}\text{In five years will} & \text{Tom} & \text{be} & \text{twice} & \text{the age than what} & \text{Sonny was 4 years ago} \\ \text{(5 +} & T\text{)} & = & 2\times & ( & S-4\text{)}\end{matrix}$

This gives two equations:
$\displaystyle T=12+S$
$\displaystyle (5+T) = 2(S-4)$

Do you know how to solve a system of two equations?
No, this is new to me. coud you help me sovle it?

8. ## Re: Algebra. Trying to learn and need help.

Originally Posted by SlipEternal
Let's use letters. For Tom, we will use T. For Sonny, we will use S.
When I was a teacher I discouraged language like that. You are really using "T" to represent Tom's age, not to represent "Tom". The same for "S". As we see at the end, "T" and "S" are numbers, not people!

The word is means equals. Older than means plus.
$\displaystyle \begin{matrix}\text{Tom} & \text{is} & 12\text{ years} & \text{older than} & \text{Sonny} \\ T & = & 12 & + & S\end{matrix}$

$\displaystyle \begin{matrix}\text{In five years will} & \text{Tom} & \text{be} & \text{twice} & \text{the age than what} & \text{Sonny was 4 years ago} \\ \text{(5 +} & T\text{)} & = & 2\times & ( & S-4\text{)}\end{matrix}$

This gives two equations:
$\displaystyle T=12+S$
$\displaystyle (5+T) = 2(S-4)$

Do you know how to solve a system of two equations?

9. ## Re: Algebra. Trying to learn and need help.

T = S + 12
5+T = 2*(S - 4) => sub in T
5+(S+12) = 2*(S - 4)

5 + S + 12 = 4S - 8 => solve for S
17 + 8 = 3S

S = 25 / 3

10. ## Re: Algebra. Trying to learn and need help.

That's wrong Sky; try again: S = 25

11. ## Re: Algebra. Trying to learn and need help.

Originally Posted by jssky
T = S + 12
5+T = 2*(S - 4) => sub in T
5+(S+12) = 2*(S - 4)

5 + S + 12 = 4S - 8 => solve for S
2*(S- 4)= 2S- 8, not 4S- 8.

17 + 8 = 3S

S = 25 / 3