a certain sum is invested at simple interest at 15 % p . a . for two years instead of investing at 10 % p . a . for the same time period . therefore the interest received is more by rs . 840 . find the sum ?
"let the sum be rs . x . ( x * 15 * 2 ) / 100 - ( x * 10 * 2 ) / 100 = 840 = > 30 x / 100 - 20 x / 100 = 840 = > 10 x / 100 = 840 = > x = 8400 . answer : a"
divide(840, divide(multiply(subtract(15, 10), const_2), const_100))