A. -(a+5)
Because the negative sign is outside the parenthesis, multiplying by -1 just removes the negative sign:
-(a+5) * -1 = a+5
B. -(-x+31)
Apply the distributive property:
-(-x+31) becomes (- -x +31) which simplifies to (x+31)
multiply that by -1 to get -x+31
C. -(4x+12)
Because the negative sign is outside the parenthesis, multiplying by -1 just removes the negative sign:
-(4x+12) * -1 = 4x+12