Question: Li deposited $17,500 into a bank account that earned simple interest each year. After 2 years, he had earned $2975 in interest. If no money was deposited into or withdrawn from the account, what was the annual interest rate? Solution: I=Prt. First, we have to find the interest / I. In the question is asked: '' he had earned $2975 in interest" so we know that the Interest/ I is $2,975. $2,975= $17,500/P*r*2/t in years (Substitute) $2,975= 35,000r (Multiply) $2,975/35,000= $35,000r/$35,000 (Divide each side by $35,000) $2,975/$35,000=0.085 Covert the decimal 0.085 to a percent. To do so multiply the decimal by 100 0.085*100= 8.5, add the percent sign and you got the answer 8.5% Li's annual interest rate is 8.5% (we were finding the rate/r)