write an equation relating rewards earned , y to total monthly purchases, x give the domain of this function.

Question

A local credit union has a debit card that rewards 3% of your total monthly purchases

Answer 1

Rewards: Y
Purchases: X

3% of Purchases means: 0.03 X
Rewards Equal to 3% of Purchases (the line above): Y = 0.03 X

Thus we found that equation: Y = 0.03 X

Domain means all possible X values. Obviously, mathematically you can purchase anything from 0 dollars all the way up to infinity. 

That is, domain  X ∈ (0, ∞)