The usual price of a pencil sold at Shop D and E is $15. During a sale, a discount of 20% is given to every pencil sold at Shop D. At Shop E, a discount of 40% is given to the 5th pencil for every 5 pencils sold. How much cheaper would it be if Vanessa buys 12 pencils from Shop D instead of Shop E?

	Shop D	Shop E
Price of 1 pencil	80%  $12	100% $15
Every 5th pencil		60% $9

Price of 1 pencil from Shop D in percentage
= 100% - 20%
= 80%

Price of 1 pencil from Shop D at 20% discount
= 80% x 15
= ⁸⁰₁₀₀ x 15 
= $12

Cost of 12 pencils from Shop D
= 12 x 12
= $144

Price of the 5th pencil from Shop E in percentage
= 100% - 40%
= 60%

Cost of 5th pencil at Shop E
= 60% x 15
= ⁶⁰₁₀₀ x 15 
= $9

Cost of 1 set of 5 pencils at Shop E
= 15 x 4 + 9
= $69

Number of sets of 5 for pencils at Shop E
= 12 ÷ 5
= 2 r 2

Cost of 2 sets of 5 pencils at Shop E
= 2 x 69
= $138

Cost of 2 pencils at Shop E
= 2 x 9
= $18

Cost of 12 pencils at Shop E
= 138 + 18
= $156

Amount cheaper if Vanessa buys 12 pencils from Shop D instead of Shop E
= 156 - 144
= $12

Answer(s): $12