The usual price of a pen sold at Shop R and S is $20. During a sale, a discount of 25% is given to every pen sold at Shop R. At Shop S, a discount of 60% is given to the 5th pen for every 5 pens sold. How much cheaper would it be if Vanessa buys 12 pens from Shop R instead of Shop S?

	Shop R	Shop S
Price of 1 pen	75%  $15	100% $20
Every 5th pen		40% $8

Price of 1 pen from Shop R in percentage
= 100% - 25%
= 75%

Price of 1 pen from Shop R at 25% discount
= 75% x 20
= ⁷⁵₁₀₀ x 20 
= $15

Cost of 12 pens from Shop R
= 12 x 15
= $180

Price of the 5th pen from Shop S in percentage
= 100% - 60%
= 40%

Cost of 5th pen at Shop S
= 40% x 20
= ⁴⁰₁₀₀ x 20 
= $8

Cost of 1 set of 5 pens at Shop S
= 20 x 4 + 8
= $88

Number of sets of 5 for pens at Shop S
= 12 ÷ 5
= 2 r 2

Cost of 2 sets of 5 pens at Shop S
= 2 x 88
= $176

Cost of 2 pens at Shop S
= 2 x 8
= $16

Cost of 12 pens at Shop S
= 176 + 16
= $192

Amount cheaper if Vanessa buys 12 pens from Shop R instead of Shop S
= 192 - 180
= $12

Answer(s): $12