every year an amount increases by 1 / 8 th of itself . how much will it be after two years if its present value is rs . 6400 ?
"6400 * 9 / 8 * 9 / 8 = 8100 answer : a"
add(add(6400, multiply(divide(1, 8), 6400)), multiply(divide(1, 8), add(6400, multiply(divide(1, 8), 6400))))