Problem: if rs . 450 amount to rs . 540 in 4 years , what will it amount to in 6 years at the same rate % per annum ?
Rationale: "90 = ( 450 * 4 * r ) / 100 r = 5 % i = ( 450 * 6 * 5 ) / 100 = 135 450 + 135 = 585 answer : c"
annotated_formula: subtract(multiply(subtract(540, 450), 6), subtract(540, 450))