Solution:
Given data in the question-
Price of per piece of napkin at an outlet store - $4.25
Discount coupon used a $20 off coupon.
[tex] y = 4.25x - 20 [/tex]
In the equation , x represents the number of napkins, and y represents the cost before tax.
She paid $43.75 before tax, which means [tex] y=43.75 [/tex]
[tex] => 43.75 = 4.25x-20\\= >43.75+20 =4.25x\\=>x=\frac{63.75}{4.25} = 15 [/tex]
Starla bought 15 napkins