Check the picture below, bear in mind that all 3 cities are colinear.
First, look at how many numbers are divisible by 2 and 3.
12,72, and 108 and are all divisible by both 2 and 3. That makes 3 out of 8 numbers.
Depending on what form you have to put the probability, that makes it 3:8, 3 out of 8, or 37.5% probability.
1. x=-3 y=4 2. x=5/2 y=15/2 3. x=9/5 y=-36/5 4. x=-2 y=1