at what rate percent per annum will the simple interest on a sum of money be 4 / 5 of the amount in 10 years ?
"let sum = x . then , s . i . = 4 x / 5 , time = 10 years . rate = ( 100 * 4 x ) / ( x * 5 * 10 ) = 8 % answer : c"
divide(multiply(divide(4, 5), const_100), 10)