I need help with this question

P= $1400,300 r = 7 1/2% t = 4 what is i ? $4.29 $429.00 $4290.00

On the april 3 billing date, michaelle chappell had a balance due of $ 1495.39 on her credit card. from april 3 through may 2, michaelle charged an additional $ 305.34 and made a payment of $ 800.a) find the finance charge on may 3, using the previous balance method. assume that the interest rate is 1.8 % per month.b) find the new balance on may 3.

What are “like terms”? why can we only add like terms?