Answer: you can make 6 costumes, and you'll run out of white fabric first.
Step by Step explanation:
1. Divide 10 by 1 1/2, which rounded down equals 6.
2. Divide 7 by 1, which equals 7
3. Divide 1 3/4 by 1/4, which equals 7.
Since he can only make 6 costumes using the white fabric that he already has, white will run out first.