A tire dealer sells 2 tires for as much as he paid for 3 tires. He paid $240 for a dozen tires. What is the total profit on 12 tires?

He paid 240 for a dozen tires (a dozen is 12) ... so he paid 240/12 = 20 per tire

he sells 2 tires for as much as he paid for 3 tires ... at 20 per tire, he paid (20 x 3) = 60 ... so he sold 2 tires for 60 ... thats 30 per tire

so he is buying the tires at 20 a piece, but selling them at 30 a piece ... so hes making a 10 dollar profit on each tire sold

so if he sold 12 tires ... the profit would be (10 * 12) = 120