Problem: adam borrowed some money at the rate of 6 % p . a . for the first two years , at the rate of 9 % p . a . for the next 3 years , and at the rate of 14 % p . a . for the period beyond 4 years . if he pays a total interest of 11900 at the end of 9 years , how much money did he borrow ?
Rationale: let the sum borrowed be x . then , ( x × 6 × 21 / 00 ) + ( x × 9 × 3 / 100 ) + ( x × 14 × 4 / 100 ) = 11900 ⇒ ( 3 ⁄ 25 x + 27 ⁄ 100 x + 14 ⁄ 25 x ) = 11400 ⇒ 95 ⁄ 100 x = 11900 ⇒ x = ( 11900 × 100 / 95 ) = 12526 hence , sum borrowed = 12,526 answer b
annotated_formula: subtract(divide(11900, add(add(divide(multiply(6, const_2), const_100), divide(multiply(9, 3), const_100)), divide(multiply(14, 4), const_100))), multiply(const_12, const_1000))