Problem: a sum of money at simple interest amounts to rs . 835 in 3 years and to rs . 854 in 4 years . the sum is :
Rationale: "s . i . for 1 year = rs . ( 854 - 835 ) = rs . 19 . s . i . for 3 years = rs . ( 19 x 3 ) = rs . 57 . principal = rs . ( 835 - 57 ) = rs . 778 . answer : c"
annotated_formula: subtract(835, divide(multiply(subtract(854, 835), 3), 4))