Mr. Ismail invested sh. 36,000 in the bank which gives an interest of 20% per year. After how long will he get sh. 43,200?

#please people help me this question how to arrive to final answer. Also i need to know if sh. 43,200 is either the total amount of money (P+I) or the interest given by the bank with reasons.
Thank you for your cooperation#

2 answers

Interest = principal times rate times time

43,000 = 36,000 * 0.2 * t

Solve for t.
This approach gives the answer in fraction, but the answer from book is 1 year.