Answer:
Set up the problem like a ratio by using fractions.
Explanation:
For every 3oz it costs $10, and you're trying to find out the amount you can get for $15.
If you set up 3/10 = x/15, you can solve for x by multiplying 3 and 15 together, giving you 45. After that, you divide 45 by 10 and you will get the answer 4.5