Question

Ann can build a model car in 5 hours, while Sam can build the same model in 15 hours. How many hours would it take for them to build the model together? (Set up the rational equation, and solve for x)

Answer 1

3 hours and 45 minutes

The equation can be solves by adding their two efforts together in a ration equation. See below. 

5/x + 15/x = 1

Then give them common denominators and add and solve.