I have a big math test tomorrow and a question on the review packet my teacher made for my class just doesn't make sense to me. Here it is...
For a 'Black Friday' sale, everything in a store is 10% off the original price. If Ana purchased an item that was marked with a sale price of $40, what was the original price?

My teacher said the answer was $44.44 but I don't understand how she got that, can someone help please?