We want to know how much is the price per pound (or unit rate) of ground beef, given that we know the price for Elliot's purchase. We will see that each pound costs $4.75
So we know that (3 + 2/5) lb of ground beef costs $16.15, the cost of a single pound will be given by the quotient between the total cost and the amount purchased, then we need to solve:
We can rewrite the denominator as:
(3 + 2/5)lb = (15/5 + 2/5)lb = (17/5) lb
Replacing that we get:
So each pound of ground beef costs $4.75
If you want to learn more about unit rates, you can read: