Which is the slope of the line y=−3x+2? y=-3x+2?

The slope is -3.
Finding slope can be easy if you just remember that the formula is set up as y=mx+b.
The number in the 'm' place is always the slope.
Example: y=4x+1, the slope would be 4 because it's in the 'm' place.
If you have trouble remembering which place the slope is, trying thinking about skiing or sledding; you can only sled or ski down a Mountain slope. Mountain starts with M.
M=slope.
Hope this helps :)
If you have any questions, just let me know!