Explanation:
To find Δy and Δx (change in y and change in x), you need to do y2-y1 and x2-x1.
Example on how to solve problem 1:
change in y: Pick 2 numbers from the y side of the table that are next to each other (it doesn't matter which 2 ). You're going to subtract the first one one the list that you picked from the second one from the list that you picked. example: 4-1= 3
change in x: repeat the same process with the x side of the table (make sure that you pick x points that go with the y, otherwise it won't work). If you picked 4-1 on the y table, the you have to pick 0- -3, which equals 3 (due to two negatives making a positive).
now, you divide your change in y by your change in x. example: 3÷3 = 1. This means that your m (slope) = 1 (on the first problem)
This kinda sounds confusing but hope this helps a bit. If not, you can look up lots of tutorials online with better explanations :)