What is the slope of a line that passes through (-2,-3) and (1, 1)

The slope of (-2, 3) & (1, 1) is ( 4, 2). The reason why the answer is (4, 2) is that if you look at a number line from left to right you'd see that -2 takes four steps to get to positive 2.

                     -10 -9 -8 -7 -6 -5 -4 -3 -2 -1  0  1 2 3 4 5 6 7 8 9 10
                                                           ↑  ↑  ↑  ↑ ↑
                                                                1  2  3 4

As for the other plot, you have to think: How many times does 1 need to jump to get to 3?

                     -10 -9 -8 -7 -6 -5 -4 -3 -2 -1  0  1 2 3 4 5 6 7 8 9 10
                                                                       ↑ ↑ ↑
                                                                          1  2 
This is important to remember, the numbers to your right is your y  and the numbers to your left is your x. 

(-2, 3) (1, 1)
       ↑      ↑
        y     y

(-2, 3) (1, 1)
  ↑       ↑
  x       x

I hope I helped :)