Problem: find the c . i . on a sum of rs . 1600 for 9 months at 20 % per annum , interest being compounded quarterly ?
Rationale: "a = 1600 ( 21 / 20 ) 3 = 2522 answer : c"
annotated_formula: subtract(multiply(1600, multiply(add(const_1, divide(const_0_25, const_4)), add(const_1, divide(const_0_25, const_4)))), 1600)