How many 20-pound boxes are in Stan's load?

Question

Stan is carrying a load of 50 boxes of books in his truck. Some of the boxes weigh 20 pounds each, and the rest of the boxes weigh 10 pounds each. if all the boxes weigh a total of 900 pounds, how many 20-pounds boxes are in Stan's load? 

Answer 1

Hi Daniel,

Let x = number of 20# boxes.

Then 20x + (50-x)(10) = 900

20x + 500 - 10x = 900

10x = 400

x = 40 boxes of 20# books