a) Thobani must pay R3,600 in cash as a deposit (20% of R18,000).
b) Thobani borrows R14,400 on the loan agreement (R18,000 - R3,600).
c) Over three years, excluding the deposit, Thobani will pay R5,184 in interest (R14,400 * 12% * 3).
d) Thobani will have to pay R400 each month (R14,400 / 36 months).
e) The total amount Thobani pays for the drums over three years is R22,584 (R18,000 + R5,184).