Question 423289
in 10 min, the hot faucet fills 1/4 (10/40) of the tub; the cold faucet fills 1/3 (10/30) of the tub;
and the drain empties 1/2 (10/20) of the tub


1/4 + 1/3 - 1/2 = 3/12 + 4/12 - 6/12 = 1/12


if it takes 10 min to fill 1/12 of the tub; it takes 120 min (12 * 10) or 2 hr to fill the whole tub