1) What is the domain if the range is 66. Range is "y" so substitute 66 for y and solve for x.
10.5x + 3 = 66 solve for x. You should get x = 6
2) What is the range if the domain is 9. Domain is "x" so substitute 9 for x and solve for y
10.5(9) + 3 = y. You should get y = 97.5