Answer: independent variable = x, Dependent variable = y, Domain = {1,2,3}, Range = {10.5, 12, 13.5}
Step-by-step explanation:
Given :  function y = 1.5x + 9 represents the cost y (in dollars) of a large pizza with a toppings, where x is equal to  1, 2, or 3.
here , independent variable = x  (Number of toppings on with cost is dependent)
Dependent variable = y
Domain = Set values of x = {1,2,3}
At x = Â 1 , y = 1.5+9 = 10.5
At x= 2 , y= Â 1.5(2) + 9 = 12
At x= 3, Â y = 1.5(3) + 9 = 13.5
Range = set of values of y = {10.5, 12, 13.5}