12% per annum means 12% for every year or every 12 months. So for every month, interest rate = 12% ÷ 12 = 1%
The interest is compounded monthly, over a period of 4 months.
Use the formula Total Amount = P(1 + r/100)ⁿ, where P is the principal sum, r% is the interest rate per compounding period, and n is the number of periods.
Total amount = $2900(1 + 1/100)⁴ = $2900(1.01)⁴ ≈ $3,017.751629 ≈ $3017.75 (nearest cent)
Interest accrued = Total amount - principal sum = $3017.75 - $2900 = $117.75