Answer:
Your friend made 35 bird houses.
Step-by-step explanation:
If the ratio from your houses to your friends houses is 4:5, that means that for every 9 houses built, your friend did 5. So, every 18 houses built, your friend did 10. For every 27, your friend did 15, and for 36, your friend did 20, and for every 45, your friend did 25, and for every 54, your friend did 30, and for every 63, your friend did 35.
