Question

Graham i just don't understand the problem i've been on it for a hour and 21 min.

Answer 1

First of all, don't start a new post every time you ask, reply to the same original one.

I assume you're referring to the problem where I answered:



"Sam's age is five years more than twice Jessica's age."

So, Sam's age, which I will designate a "s" is 5 years more than twice Jessica's age, which I will designate as "j".

From this we can realize that twice Jessica's age (2j) plus 5 is equal to Sam's age. From this, we can get the equation:

s = 2j + 5

"Together, the sum of their ages is 17."

This one's pretty straightforward:

s + j = 17

So now we have the system of equations:

s = 2j + 5

s + j = 17

Since we know that s = 2j + 5, we can substitute 2j + 5 for s in the second equation:

s + j = 17
(2j + 5) + j = 17

By using algebra to solve for J in the equation above, you will arrive at the correct answer.



Is that explanation lacking? Do you not understand the last part.

Answer 2

Yes i don't understand the last part the S suddenly disappeared im not looking for the answer of j im looking for the answer of s. I know J=4 But i can't get S

Answer 3

I am so sorry for wasting your time S=13 i got it sorry :(

Answer 4

So, J = 4, and we have the equation:

s + j = 17

You can solve this by substituting 4 for j in that equation.

Answer 5

No, you didn't waste my time, understanding is an important part of learning.

Answer 6

Good grief, bobpursely gave a perfectly good answer when you posted as 8thgradestudent as did Graham
http://www.jiskha.com/display.cgi?id=1473900151

please don't switch names, it causes the same question being answered unnecessarily .

Here is another shot at it:

Jessica's age ---- x
Sam's age ------ 2x + 5

x + x+5 = 17
2x = 12
x = 6

So Jessica is 6 and Sam is 17

Answer 7

x + 2x+5 = 17
3x = 12
x = 4

So Jessica is 4 and Sam is 13