need the domain of functions.

Question

a local bank has a debit card that gives $3 reward each month you use your card for $50 or more in purchases. I need to write an equation for x and y.  I got y= 0.03 and x=50.  Now I need the domain of each function.

Answer 1

Let x represent the amount of money spent in a month using the debit card.

Let y represent the reward earned for that month.

The bank offers $3 if x ≥ 50, and $0 if x < 50.

So the function for y in terms of x is:

y(x)= 3 if x ≥ 50

0 if x < 50

Since x represents money spent, it must be a non-negative value:

The domain of x is: x ≥ 0, or [0, ∞)

The range of y (possible outputs): {0, 3}