Question 54775
-x(a-b) [Substitute (-2) for x; (3) for a and (-1) for b within the expresssion]
-(-2)[(3)-(-1)] [Just dump the value of each letter back into the problem regardless of the sign]
.
-(-2)[(3)-(-1)] [Use the order of operations (PEMDAS) to simplify]
+2(3+1) 
2(4)
8