Answer:
Robert's interest rate is 91.46%.
Explanation:
Given that Robert has $ 645.42 on his credit card balance, but the payment he needs to make to bring his balance to $ 0 is $ 1235.18, the interest rate for non-payment that he has in his account is as follows:
645.42 = 100
1235.18 = X
((1235.18 x 100) / 645.42) = X
191.46 = X
Therefore, since 191.46 - 100 is equal to 91.46, the interest rate that this account has is 91.46%.
