Answer:
24 birdhouses
Explanation:
This is a proportional relationship. y = kx, where k is the constant of proportionality. We can determine k as follows:
4 birdhouses = k(1 1/2 hours), which leads to:
4 birdhouses
------------------------- = 8/3 birdhouses/hr
3/2 hours
In 9 hours, Ben can make (8/3)(9) birdhouses: 24 birdhouses