Explanation:
22 pounds for $11.
we could now calculate how many pounds we can buy for $1.
that would be 22/11 = 2 pounds.
or we can calculate as requested how much (how many $) he needed to pay for 1 pound.
that would be 11/22 = 1/2 = $0.50
and as you can see, both answers work prefectly together. they are just different views of the same basic problem.
we have to pay $0.50 per pound, and so we can buy 2 pounds with $1.