On a coordinate plane (-9, 2) and (-9, 10) are placed how many spot are inbetween the two

They both share the same x coordinate, meaning there is a undefined slope. So it's basically a vertical line on the X value, -9. One y value is 10 and the other two, so all you have to do is 10-2 which gives you 8.  
8 spots inbetween.