An article with a net weight of 10 lb (pounds) is packaged in a box that weighs ½ lb. If 20 of these boxed articles are put into one freight container that weighs 15 lb, what is the gross weight?

In this question, a package of 10lb was put on a box with 0.5 lb weight. That mean every box would weight : 10lb + 0.5 lb = 10.5lb per box.

Then 20 of those boxes is put on a freight container with 15lb weight. Then the total weight should be:

20 boxes * 10.5 lb/box + 15 lb = 210lb + 15 lb = 225lb

10.5 per boxed article, multiply by 20 for 20 boxed articles then add 15 which is=

(10.5*20) + 15 = 225

or