An open box is made from a piece of metal 40 cm by 50 cm by cutting a square from each corner and folding up the edges. The volume of the box is 1000 cm$^3$. (Recall that volume is area of the base times height.) What is the length of the sides of the squares?
Thus far I have that $A=l\times w$. Thus, $(40-2x)(50-2x)=A$ and volume is $l\times w\times h$. We get $1000=(40-2x)(50-2x)x$. Is this correct? How do I solve the cubed equation then?