Answer:
y = 9x
Step-by-step explanation:
You can set up linear equations like this: y = mx + b, where m is the slope or rate, and b is the y-intercept.
9 would be the slope, since he has to pay $9 per gift.
The y-intercept is when x = 0, but if he doesn't buy any gifts, he won't have to pay anything, so b = 0. You don't have to include it since it's 0.
So, it's just y = 9x
Hope that helps! :D
