Distributive property:
Multiply all the inside terms by the outside term. So
-12(-w+4) = -12*(-w) -12*(4) = 12w - 48
The answer is 12w - 48
8(6f-1) = 8*6f + 8*(-1) = 48f - 8
-(5a+7) = -(5a) -(+7) = -5a - 7
14(x + y) = 14*x + 14*y = 14x + 14y
-5t(2u + 4) = -5t*2u - 5t*4 = -10ut - 20t