Dominique can ice cupcakes twice as fast as Houston. When they work together, Dominique and Houston can ice a large order of cupcakes in 5 hours. How many hours would it take Houston to ice them by himself?

1

4

thirteen-halves

fifteen-halves

This is a work problem. It can be solved as follows:

Houston = 1/x

Dominique = (1/2x)

Together = 1/5

Then, we add Houston and Dominique:

1/x + 1/2x = 1/5

Solve for x,

x = 2/15

Therefore, it would take 15/2 hours for Houston to ice by himself, the last option.