Question

How do you solve the system -3(5+x)=y and 5(x-3)=2y+4?

Answer 1

`(x,y) = (-1,-12)`

Explanation:

Given:
[1]`color(white)("XXXX")` `-3(5+x)=y`
[2]`color(white)("XXXX")` `5(x-3)=2y+4`

Replace `y` in [2] with `-3(5+x)` as specified in [1]
[3]`color(white)("XXXX")` `5(x-3)=2(-3(5+x))+4`

Simplifying
[4]`color(white)("XXXX")` `5x-15 = -30-6x+4`
[5]`color(white)("XXXX")` `11x = -11`
[6]`color(white)("XXXX")` `x = -1`

Substituting `x=-1` back in [1]
[7]`color(white)("XXXX")` `-3(5-1) = y`
[8]`color(white)("XXXX")` `y = -12`