Problem: one pipe can fill a tank three times as fast as another pipe . if together the two pipes can fill tank in 35 min , then the slower pipe alone will be able to fill the tank in ?
Rationale: "let the slower pipe alone fill the tank in x min . then , faster pipe will fill it in x / 3 min . 1 / x + 3 / x = 1 / 35 4 / x = 1 / 35 = > x = 140 min . answer : e"
annotated_formula: multiply(add(const_1, const_4), 35)