one pipe can fill a tank three times as fast as another pipe . if together the two pipes can fill the tank in 38 minutes , then the slower pipe alone will be able to fill the tank in
"explanation : let the slower pipe alone fill the tank in x minutes then faster will fill in x / 3 minutes . part filled by slower pipe in 1 minute = 1 / x part filled by faster pipe in 1 minute = 3 / x part filled by both in 1 minute = 1 / x + 3 / x = 1 / 38 = > 4 / x = 1 / 38 x = 38 ∗ 4 = 152 mins option d"
multiply(add(const_1, const_4), 38)