Answer:
4 feet and 2 inches
Explanation:
First, find the difference between the number of feet in their throws:
21 - 17
= 4 feet
Since Bill's throw had 6 inches while John had 4 inches, subtract 2 inches from the 4 feet that we calculated earlier.
This gets us 4 feet and 2 inches, since there are 12 inches in a foot.
So, Bill's throw was 4 feet and 2 inches greater than John's.