3.Slope: 10 Y int: 5
4. Slope: 5 Y int: 10
6.Slope: 1/3 Y int: 3.5
7.Slope: 4/3 Y int: -1
8.Slope: 2/-4 Y int: -1
The way you do this is the Y int is where the line crosses through the y-axis. Finding the slope is finding the rise over run (y/x). It's easy to find when you know how to.
Use 4. as an example. Start where at (-3,-5) or (-2,0). Each 'rise' up 5 and 'runs' one block over, giving you the slope of 5/1 or 5 simplified.
7 is harder, but start at (-3,-5). It 'rises' up 4, then 'runs' 3, also giving you the y int, as it crosses the axis. As the rise is 4 and run is 3, it creates the slope 4/3.