Inactive Tutor answered 07/19/19
Tutor
New to Wyzant
Let x be the price of 1 article.
Normally 3 articles cost 3x and 4 articles cost 4x.
Selling 3 for 4x is a price difference of 4x-3x)=x <--- profit
x/3x = 1/3 = 33 and 1/3 % profit