a fill pipe can fill 1 / 4 of cistern in 16 minutes in how many minutes , it can fill 3 / 4 of the cistern ?
"1 / 4 of the cistern can fill in 16 min 3 / 4 of the cistern can fill in = 16 * 4 * 3 / 4 = 48 min answer is a"
divide(16, 1)