The usual price of a pencil sold at Shop B and C is $10. During a sale, a discount of 20% is given to every pencil sold at Shop B. At Shop C, a discount of 50% is given to the 6th pencil for every 6 pencils sold. How much cheaper would it be if Dana buys 16 pencils from Shop B instead of Shop C?

	Shop B	Shop C
Price of 1 pencil	80%  $8	100% $10
Every 6th pencil		50% $5

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

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

Cost of 16 pencils from Shop B
= 16 x 8
= $128

Price of the 6th pencil from Shop C in percentage
= 100% - 50%
= 50%

Cost of 6th pencil at Shop C
= 50% x 10
= ⁵⁰₁₀₀ x 10 
= $5

Cost of 1 set of 6 pencils at Shop C
= 10 x 5 + 5
= $55

Number of sets of 6 for pencils at Shop C
= 16 ÷ 6
= 2 r 4

Cost of 2 sets of 6 pencils at Shop C
= 2 x 55
= $110

Cost of 4 pencils at Shop C
= 4 x 5
= $20

Cost of 16 pencils at Shop C
= 110 + 20
= $130

Amount cheaper if Dana buys 16 pencils from Shop B instead of Shop C
= 130 - 128
= $2

Answer(s): $2