I like to separate problems into small steps that are easy to follow. In this example these would be: STEP 1: make y the subject (meaning only y on the Left hand side - LHS); 3y = -5x - 3. STEP 2: divide by 3 to isolate y; y = -(5/3)x - 1. We now have our solution. M is the coefficient of x in our final equation, -5/3.