Hello there! I can help you! The formula for simple interest is prt. We multiply the principal (inital amount) by the interest rate (in decimal form) by the time (could be in months or years). For this expression, our principal is $360. The interest rate is 12.3% (0.123 in decimal form). We will multiply those two numbers first. 360 *12.3% is 44.28. That's $44.28 in interest per year, but we're not done. Now, we multiply that by the amount of time, which is 30 months. In this case, we will convert that to years. 30/12 is 2.5. That is 2.5. We will multiply the interest by 2.5. 44.28 * 2.5 is 110.7. There. The simple interest is $110.70.