You can use many methods, I like to use the multiplier method for these questions. 6% = 0.06. Because it increase you add it to 1, if it decreased you’d subtract from 1. So 1200 x 1.06^ 4 (to the power of 4). 1514.972352. But because you can’t half a decimal of a person you’d round it to the next whole number so 1515.