Given :
Cost of single bottle, C = $1.69 .
Cost of 4 bottles, B = $5 .
You bought one bottle last week for $1.69 and one bottle this week at the 4 for $5 price.
To Find :
Did you pay more or less for the bottle this week at 4 for $5? How much more or less?
Solution :
Effective price per bottle if we purchase 4 is, E = 5/4 = $1.25 .
Regular price, R = $1.69 .
Change in price, C = $( 1.69 - 1.25 ) = $0.44 .
Therefore, we are paying $0.44 less than the actual price.
Hence, this is the required solution.