If Carson charges $7 per hour for yard work how do I write a function notation

If each hour was x and the total amount of money he charges is y than you can write it like this:

7x=y

because it's 7 each hour to get the total

F (x) = 7x, because you just write it as if it was y=7x (where 7 is the amount of money and x is the amount of time). So you would just write f of x, f (x), instead of y.