Answer:
15
Explanation:
To find the total number of combinations you can make with these four coins, we have to do 2 to the power of the total amount of coins. This because each coin has two choices: to be included in the combination or not. There are 4 total coins, and 2^4 is 16. There are 16 total combinations. But since one of those possibilities are that none of the coins are included, we subtract 1 from the total, and get 15. There are 15 combinations with 1 or more coins, which each give us different amounts.