The usual price of a notebook sold at Shop U and V is $40. During a sale, a discount of 20% is given to every notebook sold at Shop U. At Shop V, a discount of 50% is given to the 4th notebook for every 4 notebooks sold. How much cheaper would it be if Olivia buys 14 notebooks from Shop U instead of Shop V?

	Shop U	Shop V
Price of 1 notebook	80%  $32	100% $40
Every 4th notebook		50% $20

Price of 1 notebook from Shop U in percentage
= 100% - 20%
= 80%

Price of 1 notebook from Shop U at 20% discount
= 80% x 40
= ⁸⁰₁₀₀ x 40 
= $32

Cost of 14 notebooks from Shop U
= 14 x 32
= $448

Price of the 4th notebook from Shop V in percentage
= 100% - 50%
= 50%

Cost of 4th notebook at Shop V
= 50% x 40
= ⁵⁰₁₀₀ x 40 
= $20

Cost of 1 set of 4 notebooks at Shop V
= 40 x 3 + 20
= $140

Number of sets of 4 for notebooks at Shop V
= 14 ÷ 4
= 3 r 2

Cost of 3 sets of 4 notebooks at Shop V
= 3 x 140
= $420

Cost of 2 notebooks at Shop V
= 2 x 20
= $40

Cost of 14 notebooks at Shop V
= 420 + 40
= $460

Amount cheaper if Olivia buys 14 notebooks from Shop U instead of Shop V
= 460 - 448
= $12

Answer(s): $12