For these problems, you can plug in the value of y for the variable and solve by isolating x.
When y = -3, the equation would be -3 = -1.5x.
To isolate x, divide both sides by -1.5.
-3 / -1.5 = 2
So this means when y = -3, x = 2.
Now do the same for y = 4.5 and y = 6.
4.5 = -1.5x
4.5 / -1.5 = -3
When y = 4.5, x = -3.
6 = -1.5x
6 / -1.5 = -4
When y = 6, x = -4.
Hope this helps! :)