Question

Which expression is equivalent to (-4-x)-(3y-9x)

Answer 1

Basically, you just need to simplify it first, then combine like terms. 
(-4-x)-(3y-9x)
   = -4 - x - (3y - 9x)
   = -4 - x + -1(3y) + -1 (-9x)
   = -4 + -x + -1(3y) + -1(-9x)
   = -4 + -x + -3y + 9x
   = (-x + -9x) + (-3y) + (-4)
   = 8x + (-3y) + (-4)
   = 8x - 3y - 4 

Answer 2

(-4-x)-(3y-9x)
= -4 - x - 3y + 9x
= 8x - 3y - 4