Harry purchased 18 hinges for his kitchen project. They were each on sale for $4 off the regular price. The total cost of the hinges was $90. What was the regular price for each hinge?

Answer: $ 9

Step-by-step explanation:

Let the regular price of one hinge = x dollar,

After $ 4 off, the new price of one hinge = x-4 dollars

Thus, the price of 18 hinges = 18 (x-4) dollars,

But, According to the question,

The price of 18 hinges = $ 90

⇒ 18 (x-4) = 90

⇒ x-4 = 5

⇒ x = 9

Hence, the regular price of each hinge = $ 9