if I solve this by substitution

Question

8x+7y=-13
x=29-7y
I end up with -3.8

But I think there is no solution

Answer 1

sub the 2nd into the 1st

8(29-7y) + 7y = -13
232 - 56y + 7y = -13
-49y = -245
y = 245/49 = 5

then x = 29 - 7(5) = -6

Answer 2

You should have questioned your "no solution" answer, since the lines have different slopes. The have to intersect somewhere.