a tank is filled by 3 pipes a , b , c in 4 hours . pipe c is twice as fast as b and b is twice as fast as a . how much will pipe a alone take to fill the tank ?
"suppose pipe a alone take x hours to fill the tank then pipe b and c will take x / 2 and x / 4 hours respectively to fill the tank . 1 / x + 2 / x + 4 / x = 1 / 4 7 / x = 1 / 4 x = 28 hours answer is e"
multiply(add(add(multiply(const_2, const_2), const_2), const_1), 4)