1. **Problem 4:** Calculate the simple interest Maria pays after 1 year. Simple interest formula is $$I = P imes r imes t$$ where: - $P$ is principal - $r$ is annual interest rate in decimal - $t$ is time in years Given: $P = 25000$, $r = 12\% = 0.12$, $t=1$ Calculate: $$I = 25000 \times 0.12 \times 1 = 3000$$ So, interest after 1 year is ₱3000. 2. **Problem 5:** Calculate total amount Maria should return after 1 year. Amount $A$ is principal plus interest: $$A = P + I = 25000 + 3000 = 28000$$ Maria should pay ₱28000. 3. **Problem 6:** Calculate the amount Minda should pay after 8 months with 5% per annum simple interest. Convert 8 months to years: $$t = \frac{8}{12} = \frac{2}{3}$$ Given $P=9000$, $r=5\% = 0.05$ Interest: $$I = 9000 \times 0.05 \times \frac{2}{3} = 300$$ Total amount: $$A = P + I = 9000 + 300 = 9300$$ 4. **Problem 7:** Find total interest Minda pays. As calculated above, interest $I$ is ₱300. **Final answers:** 4) ₱3000 5) ₱28000 6) ₱9300 7) ₱300