I just wanted to know if this was correct, here's the question... there's an open top box with the volume of 9m^3 and the length of its base is triple its width. The thick wood used for the base is $8/m^2 and thinner wood for sides is $5/m^2. (a)Express the cost of wood as a function of the width of the base. (b)if you had $144 to spend, what dimensions would the box be to keep the volume at 9m^3. (c)What dimensions would be best?

well I have no clue for the last question (c) but for question (a) I got f(w)=24w^2 + 120/w
for (b) I got V=(area)(height)=24(w^3+5+6w)... is any of this right?