The usual price of a pen sold at Shop E and F is $25. During a sale, a discount of 20% is given to every pen sold at Shop E. At Shop F, a discount of 40% is given to the 4th pen for every 4 pens sold. How much cheaper would it be if Abi buys 14 pens from Shop E instead of Shop F?

	Shop E	Shop F
Price of 1 pen	80%  $20	100% $25
Every 4th pen		60% $15

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

Price of 1 pen from Shop E at 20% discount
= 80% x 25
= ⁸⁰₁₀₀ x 25 
= $20

Cost of 14 pens from Shop E
= 14 x 20
= $280

Price of the 4th pen from Shop F in percentage
= 100% - 40%
= 60%

Cost of 4th pen at Shop F
= 60% x 25
= ⁶⁰₁₀₀ x 25 
= $15

Cost of 1 set of 4 pens at Shop F
= 25 x 3 + 15
= $90

Number of sets of 4 for pens at Shop F
= 14 ÷ 4
= 3 r 2

Cost of 3 sets of 4 pens at Shop F
= 3 x 90
= $270

Cost of 2 pens at Shop F
= 2 x 15
= $30

Cost of 14 pens at Shop F
= 270 + 30
= $300

Amount cheaper if Abi buys 14 pens from Shop E instead of Shop F
= 300 - 280
= $20

Answer(s): $20