Answer:
Explanation:
2.50 for water
1.25 for protein bar interesting that is exactly half of the water
22.50 exactly was spent
I couldn't come up a slick equation, so I just applied some logic and used brute forced (trail and error) to solve the problem.
2.5Water + 1.25Protein = 22.5
8W + 2P = 22.5
6W + 6P = 22.5
4W + 10P = 22.5
2W + 14P = 22.5
There are the possible combinations of both protein bars AND water, since he bought both. He could have also bought 10 water or 18 protein bars, but that is not part of the combination.