The usual price of a notebook sold at Shop N and P is $10. During a sale, a discount of 20% is given to every notebook sold at Shop N. At Shop P, a discount of 30% is given to the 6th notebook for every 6 notebooks sold. How much cheaper would it be if Irene buys 14 notebooks from Shop N instead of Shop P?

	Shop N	Shop P
Price of 1 notebook	80%  $8	100% $10
Every 6th notebook		70% $7

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

Price of 1 notebook from Shop N at 20% discount
= 80% x 10
= ⁸⁰₁₀₀ x 10 
= $8

Cost of 14 notebooks from Shop N
= 14 x 8
= $112

Price of the 6th notebook from Shop P in percentage
= 100% - 30%
= 70%

Cost of 6th notebook at Shop P
= 70% x 10
= ⁷⁰₁₀₀ x 10 
= $7

Cost of 1 set of 6 notebooks at Shop P
= 10 x 5 + 7
= $57

Number of sets of 6 for notebooks at Shop P
= 14 ÷ 6
= 2 r 2

Cost of 2 sets of 6 notebooks at Shop P
= 2 x 57
= $114

Cost of 2 notebooks at Shop P
= 2 x 7
= $14

Cost of 14 notebooks at Shop P
= 114 + 14
= $128

Amount cheaper if Irene buys 14 notebooks from Shop N instead of Shop P
= 128 - 112
= $16

Answer(s): $16