Problem: one copy machine can make 30 copies a minute , and a second copy machine makes 15 copies a minute . if the two copiers work together , how long would it take them to make 900 copies ?
Rationale: "total work done by both machines in a minute = 30 + 15 = 45 copies total number of copies required = 900 time = 900 / 45 = 20 mins answer b"
annotated_formula: divide(power(15, const_3), add(30, 15))