The usual price of a marker sold at Shop Y and Z is $35. During a sale, a discount of 20% is given to every marker sold at Shop Y. At Shop Z, a discount of 40% is given to the 4th marker for every 4 markers sold. How much cheaper would it be if Emily buys 11 markers from Shop Y instead of Shop Z?

	Shop Y	Shop Z
Price of 1 marker	80%  $28	100% $35
Every 4th marker		60% $21

Price of 1 marker from Shop Y in percentage
= 100% - 20%
= 80%

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

Cost of 11 markers from Shop Y
= 11 x 28
= $308

Price of the 4th marker from Shop Z in percentage
= 100% - 40%
= 60%

Cost of 4th marker at Shop Z
= 60% x 35
= ⁶⁰₁₀₀ x 35 
= $21

Cost of 1 set of 4 markers at Shop Z
= 35 x 3 + 21
= $126

Number of sets of 4 for markers at Shop Z
= 11 ÷ 4
= 2 r 3

Cost of 2 sets of 4 markers at Shop Z
= 2 x 126
= $252

Cost of 3 markers at Shop Z
= 3 x 21
= $63

Cost of 11 markers at Shop Z
= 252 + 63
= $315

Amount cheaper if Emily buys 11 markers from Shop Y instead of Shop Z
= 315 - 308
= $7

Answer(s): $7