Introduction to Formulas

If $y=2x+3$, what is $y$ when $x=3$?

The formula for the distance traveled by a car is $y=60x+120$, where $y$ is the distance in miles and $x$ is the number of hours driven. How far will it travel after 3 hours?

If $y=4x-7$, what is $x$ when $y=13$?

A company’s total revenue $y$ is represented by $y=500x-200$, where $x$ is the number of products sold. How many products must be sold to reach a revenue of $\pounds 4800$?

The total cost of a gym membership is calculated by $y=30x+50$, where $x$ is the number of months and $y$ is the total cost in pounds. If the total cost is $\pounds 200$, how many months did the member sign up for?

A company charges a $200 setup fee and $50 for printing each book. If you print more than 10 books, you get a 10% discount on the total cost. How many books can be printed for $720?