A.) y= 5x + 4 b.) y= -x + 8 c.) y= x - 10 d.) y= -4x + 3

Option B is your answer. 

If you plug it in, you get:

1 = -(7) + 8
1 = - 7 + 8
1 = 1, a true statement. 

Try the x and y values in the equations and see which works.
  A.) 1 = 5*7 +4 . . . . nope
  B.) 1 = -7 +8 . . . . . true
  C.) 1 = 7 -10 . . . . . nope
  D.) 1 = -4*7 +3 . . . nope

The appropriate choice is ...
  B.) y = -x +8

Where’s the following prism