Vicky was charged $456 interest for 1 month on a $2400 credit card balance. What was the monthly rate?

The monthly rate was 19%.

let x represents the % of monthly interest rate

Vicky was charged $456 interest for 1 month on a $2400 credit card balance.

x% x 2400 = 456

x = (456/2400) x 100

x = 456/24

x = 19

19% was the monthly rate.