Sam's age is five years more than twice Jessica's age. Together, the sum of their ages is 17. Let J = Jessica's age?

3 answers

S=5+2J
S+J=17

s-2J=5
s+J=17

subtract first equation from second
3J=12
J=4
"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.
I don't get how i still get the answer