Suppose we have a function, y=Cx where C is a constant. we take the derivative of both sides: dy/dx = d/dx (Cx) = C so dy/dx = C Then, we multiply both sides by dx: dy = Cdx Then supposed we want to get back to the original equation via integration--we integrate the right side with respect to x, but what do we integrate the left side with rexpect to? It seems it would have to be y, but how can we integrate one side with respect to x and the other with respect to y? Please advise. Thanks!!