It is a case of simplifying this expression: a^2 - ab / ab The solution given in a textbook is: a - b / b I observe that for the one "a" that was canceled below, two "a's" were canceled above in this simplification. Why would the solution not be: a^2 - b / b? I would like to know what happened to the a in a^2 if the textbook answer is the correct answer. I am also having problems simplifying this expression: 3y^2 - 27 / 12y^2 + 36y I have tried factorizing to find common factors that cancel each other out but have not had any success.... I know what the solution is but I would like to know how to get there.