Megan completes most puzzles in 24 minutes. Hassan completes most puzzles in 16 minutes. If Megan and Hassan complete a puzzle together, how long will it take?
M = 1/24 puzzle/min
H = 1/16 puzzle/min
together 1/24 + 1/16 puzzle/min
= 2/48 + 3/48 = 5/48 puzzle/min
so
48/5 min/puzzle = 9.6 minutes