one tap , working alone at its maximum constant rate , can fill a certain sink in 287 seconds . a second tap , working alone at its maximum constant rate , can fill the same sink in 283 seconds . if both taps work together at their respective maximum constant rates , the time it will take to fill the sink is closest to
tap 1 : 283 secs tap 2 : 287 secs considering the average of these 2 taps : 285 secs . so 1 tap can fill the tank in 285 secs , so 2 taps can fill the tank in 285 / 2 = 142.5 secs . closest answer is a .
divide(const_1, add(divide(const_1, 287), divide(const_1, 283)))