20 pounds of sand will be required to cover a sandbox with a W of 8 and a L or 10.
To solve this question, first we calculate the area of the sandbox (A=LW)(8*10=80). If our sandbox requires 80 square feet of sand, then all we need to do is divide our area by the amount of square feet one pound of sand covers. (80/4=20). This means that it would require 20 pounds of sand to cover our 80 square foot sandbox.