The usual price of a marker sold at Shop A and B is $36. During a sale, a discount of 25% is given to every marker sold at Shop A. At Shop B, a discount of 50% is given to the 4th marker for every 4 markers sold. How much cheaper would it be if Tiffany buys 15 markers from Shop A instead of Shop B?

	Shop A	Shop B
Price of 1 marker	75%  $27	100% $36
Every 4th marker		50% $18

Price of 1 marker from Shop A in percentage
= 100% - 25%
= 75%

Price of 1 marker from Shop A at 25% discount
= 75% x 36
= ⁷⁵₁₀₀ x 36 
= $27

Cost of 15 markers from Shop A
= 15 x 27
= $405

Price of the 4th marker from Shop B in percentage
= 100% - 50%
= 50%

Cost of 4th marker at Shop B
= 50% x 36
= ⁵⁰₁₀₀ x 36 
= $18

Cost of 1 set of 4 markers at Shop B
= 36 x 3 + 18
= $126

Number of sets of 4 for markers at Shop B
= 15 ÷ 4
= 3 r 3

Cost of 3 sets of 4 markers at Shop B
= 3 x 126
= $378

Cost of 3 markers at Shop B
= 3 x 18
= $54

Cost of 15 markers at Shop B
= 378 + 54
= $432

Amount cheaper if Tiffany buys 15 markers from Shop A instead of Shop B
= 432 - 405
= $27

Answer(s): $27