#### Explanation:

Consider the word 'unit' in unit price.

In this context we need the price of unit measurement apples.
As the measurement for apples is in pounds we need to find the cost of 1 pound.

$\textcolor{b l u e}{\text{This is one method of several}}$

Using ratio but in fractional form we have:

("cost")/("weight") -> ($17.50)/(8lb) But we need the cost of $1 l b$so we need to find a way of changing the 8 into 1. Divide 8 by 8 and you get 1. In ratios, to maintain the correct proportion if I divide the bottom by 8 I must do the same to the top. ("cost")/("weight") -> ($17.50)/(8lb)-=($17.50-:8)/(8lb-:8) = ($2.1875)/(1lb)

The $\equiv$ means equivalent to.

So the cost of $1 l b$ of apples is $2.1875 Rounding to 2 decimal places this is $2.19