Factorise the expression.
volume = height * width * depth =
Find the other two factors (ax+b), (cx+d).
One way to do this is to divide the original expression by the known factor (x-2), which will give you a quadratic expression. You can factorise the quadratic expression using the quadratic formula or any other method you have been taught.
There may be easier ways to do this if the question has given you hints about the relationship between depth, width, height.
You can deduce the factors quickly if you are allowed to assume that all the coefficients are integers (as it happens, the correct answer does have integer values of a,b,c,d).