The usual price of a notebook sold at Shop L and M is $30. During a sale, a discount of 20% is given to every notebook sold at Shop L. At Shop M, a discount of 50% is given to the 6th notebook for every 6 notebooks sold. How much cheaper would it be if Jen buys 16 notebooks from Shop L instead of Shop M?

	Shop L	Shop M
Price of 1 notebook	80%  $24	100% $30
Every 6th notebook		50% $15

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

Price of 1 notebook from Shop L at 20% discount
= 80% x 30
= ⁸⁰₁₀₀ x 30 
= $24

Cost of 16 notebooks from Shop L
= 16 x 24
= $384

Price of the 6th notebook from Shop M in percentage
= 100% - 50%
= 50%

Cost of 6th notebook at Shop M
= 50% x 30
= ⁵⁰₁₀₀ x 30 
= $15

Cost of 1 set of 6 notebooks at Shop M
= 30 x 5 + 15
= $165

Number of sets of 6 for notebooks at Shop M
= 16 ÷ 6
= 2 r 4

Cost of 2 sets of 6 notebooks at Shop M
= 2 x 165
= $330

Cost of 4 notebooks at Shop M
= 4 x 15
= $60

Cost of 16 notebooks at Shop M
= 330 + 60
= $390

Amount cheaper if Jen buys 16 notebooks from Shop L instead of Shop M
= 390 - 384
= $6

Answer(s): $6