Simplify: 5/4x-8y-1/4x+7y+3 a)x-y+3 b)3/2x+y+3 c)3/2x-y+3 d)x+y+3

A)x-y+3 is your answer 

Proof:

(5 x)/4 - 8 y - x/4 + 7 y + 3
Put each term in (5 x)/4 - 8 y - x/4 + 7 y + 3 over the common denominator 4: (5 x)/4 - 8 y - x/4 + 7 y + 3 = (5 x)/4 - (32 y)/4 - (x)/4 + (28 y)/4 + 12/4:
(5 x)/4 - (32 y)/4 - x/4 + (28 y)/4 + 12/4
(5 x)/4 - (32 y)/4 - x/4 + (28 y)/4 + 12/4 = (5 x - 32 y - x + 28 y + 12)/4:
(5 x - 32 y - x + 28 y + 12)/4
Grouping like terms, 5 x - 32 y - x + 28 y + 12 = (28 y - 32 y) + (5 x - x) + 12:
((28 y - 32 y) + (5 x - x) + 12)/4
28 y - 32 y = -4 y:
(-4 y + (5 x - x) + 12)/4
5 x - x = 4 x:
(-4 y + 4 x + 12)/4
Factor 4 out of -4 y + 4 x + 12:
(4 (-y + x + 3))/4
(4 (-y + x + 3))/4 = 4/4×(3 + x - y) = 3 + x - y:
  3 + x - y