how do i solve this? using elimination or substitution?

2x-3y=-1/12
y=-x+7/12

well, since one equation says y=... I'd use substitution.

2x - 3(-x + 7/12) = -1/12
2x + 3x - 21/12 = -1/12
5x = 20/12
x = 4/12 = 1/3

using elimination, rearrange things a bit first to get

2x-3y = -1/12
x+y= 7/12

2x-3y = -1/12
3x+3y = 21/12
add to get
5x = 20/12
x = 4/12 = 1/3