Gary's unpaid credit card balance is $2543.32. his apr is 17.4% and he made one new transaction for $320. what is his new balance?

Given that Gary's unpaid credit card balance is $2543.32. His APR is 17.4% and he made one new transaction for $320. so his new balance can be solved by just adding the unpaid credit card balance and the new transaction he made.
new balance =  $ 2543.32 + $ 320
new balance = $ 2863.32

The correct awnser is 29.76 pounds.