Answer and Explanation:
The computation of the unit price is shown below:
The First one is 20 ounce i.e. for 1.50 dollars. 
 Therefore for one ounce is 
= 1.50 ÷ 20
= 0.075 dollars 
 The Second one is 24 ounce i.e. for 1.75 dollars. 
 Therefore for one ounce is 
= 1.75 ÷ 24
= 0.0729 dollars 
 Thus, the second one is cheaper i.e. best buy