15. John gathered 12 eggs on Monday. On Tuesday, he gathered 1/2 of that amount. On Wednesday, he gathered 1/2 of the amount of eggs that he gathered on Tuesday. How many eggs did he gather on Wednesday?

 

First we have to figure out how many eggs John gathered on Tuesday. 1/2 of 12 is 6. On Wednesday he gathered half of that, and 1/2 of 6 is 3. So altogether, John gathered 12 + 6 + 3 = 21 eggs.