find the compound interest on $ 16,000 at 20 % per annum for 9 months , compounded quarterly
"principal = $ 16000 ; time = 9 months = 3 quarters ; rate = 20 % per annum = 5 % per quarter . amount = $ [ 16000 x ( 1 + ( 5 / 100 ) ) ^ 3 ] = $ 18522 . ci . = $ ( 18522 - 16000 ) = $ 2522 . answer d ."
subtract(multiply(16,000, power(add(const_1, divide(9, const_100)), 20)), 16,000)