The usual price of a pen sold at Shop P and Q is $35. During a sale, a discount of 20% is given to every pen sold at Shop P. At Shop Q, a discount of 40% is given to the 6th pen for every 6 pens sold. How much cheaper would it be if Abi buys 16 pens from Shop P instead of Shop Q?

	Shop P	Shop Q
Price of 1 pen	80%  $28	100% $35
Every 6th pen		60% $21

Price of 1 pen from Shop P in percentage
= 100% - 20%
= 80%

Price of 1 pen from Shop P at 20% discount
= 80% x 35
= ⁸⁰₁₀₀ x 35 
= $28

Cost of 16 pens from Shop P
= 16 x 28
= $448

Price of the 6th pen from Shop Q in percentage
= 100% - 40%
= 60%

Cost of 6th pen at Shop Q
= 60% x 35
= ⁶⁰₁₀₀ x 35 
= $21

Cost of 1 set of 6 pens at Shop Q
= 35 x 5 + 21
= $196

Number of sets of 6 for pens at Shop Q
= 16 ÷ 6
= 2 r 4

Cost of 2 sets of 6 pens at Shop Q
= 2 x 196
= $392

Cost of 4 pens at Shop Q
= 4 x 21
= $84

Cost of 16 pens at Shop Q
= 392 + 84
= $476

Amount cheaper if Abi buys 16 pens from Shop P instead of Shop Q
= 476 - 448
= $28

Answer(s): $28