Hi!
We will solve this using proportions. Let x be the cost for 12 ounces of cheese. We will start like this:
15 ounces : 6 $ = 12 ounces : x $
x $ = (6 $ * 12 ounces)/15 ounces
x $ = 72 $/15
x = 4,8$
The cost of 12 ounces of cheese is 4,8$.
Hope this helps!