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a) Calculate: i) the simple interest on N$1200 for 3 years at 6% per annum ii) the length of time for N$400 to earn N$160 if invested at 8% per annum b) George invested N $19000 for 8 years at 9% p.a. interest, compounded monthly. What is the value of this investment? (5) c) Sarah saves N$400 the first month and every month later N$45 more. John saves Four dollars and thirty five cents the first month and every month later he doubles the amount. Who will have more after a year and a half