the number of 5-cent coins in a money box is 2 less than three times the number of 10-cent coins. The total value of coins is $4.40. How many 5-cent coins are there in a box?

Answers here are indeed 'free' but that doesn't mean we do your work for you. You are expected to try. As you know, you need to set up a formula with 4.40 as the result. How would you start?