Answer:
C) 18 cents
Step-by-step explanation:
Given,
This weeks deal - 
Quantity of Flour      Price ($)         Price per pound ($)
3 pounds                    5.25                 (5.25/3) =  1.75
5 pounds                    9.75                 (9.75/3) =   1.95
7 pounds                    12.60                (12.60/3) = 1.80
10 pounds                  14.20                 (14.20/3) = 1.42
12 pounds                  18.24                 (18.24/3) = 1.52
The lowest price per pound is $1.42. Therefore, this is the current week's best deal.
The last week's best deal was = $`1.60/pound
The difference between the unit price for previous week's best deal and this week's best deal = $1.60 - $1.42 = $0.18
Therefore, 18 cents.