The usual price of a notebook sold at Shop W and X is $40. During a sale, a discount of 25% is given to every notebook sold at Shop W. At Shop X, a discount of 60% is given to the 4th notebook for every 4 notebooks sold. How much cheaper would it be if Xylia buys 10 notebooks from Shop W instead of Shop X?

	Shop W	Shop X
Price of 1 notebook	75%  $30	100% $40
Every 4th notebook		40% $16

Price of 1 notebook from Shop W in percentage
= 100% - 25%
= 75%

Price of 1 notebook from Shop W at 25% discount
= 75% x 40
= ⁷⁵₁₀₀ x 40 
= $30

Cost of 10 notebooks from Shop W
= 10 x 30
= $300

Price of the 4th notebook from Shop X in percentage
= 100% - 60%
= 40%

Cost of 4th notebook at Shop X
= 40% x 40
= ⁴⁰₁₀₀ x 40 
= $16

Cost of 1 set of 4 notebooks at Shop X
= 40 x 3 + 16
= $136

Number of sets of 4 for notebooks at Shop X
= 10 ÷ 4
= 2 r 2

Cost of 2 sets of 4 notebooks at Shop X
= 2 x 136
= $272

Cost of 2 notebooks at Shop X
= 2 x 16
= $32

Cost of 10 notebooks at Shop X
= 272 + 32
= $304

Amount cheaper if Xylia buys 10 notebooks from Shop W instead of Shop X
= 304 - 300
= $4

Answer(s): $4