The slope of that line is -1, so m = -1.
The point you were told to use is (-2,2), so point-slope form starts as:
( y - 2 ) = -1 • ( x - (-2) )
But we'd clean up that x-(-2) to be x+2.
y - 2 = -1 ( x+2 )
First turns those into fractions, now you should have 4/5 and 1/5.
Now to generate a chance the 2 events will happen in a row (Like rain and a postponed game) you need to multiply the 2 fractions together so it should come out with 4/25 or 16%