Problem: a cistern can be filled by a tap in 5 hours while it can be emptied by another tap in 10 hours . if both the taps are opened simultaneously then after how much time will the cistern get filled ?
Rationale: "net part filled in 1 hour 1 / 5 - 1 / 10 = 1 / 10 the cistern will be filled in 10 hr answer is b"
annotated_formula: divide(const_1, subtract(divide(const_1, 5), divide(const_1, 10)))