Adding a negative is same as subtraction
-5+78-32
73-32
41
(-2.5,6.1)(-2.5,3.1).....notice how ur x values are the same. This means that u have a vertical line which has an undefined slope.
IF ur y values would have been the same, u would have had a horizontal line which has a 0 slope.
We have 35 - 5 = 30 levels left to beat.
The question is asking us for the levels left to beat, to the ones that already have been beaten:
30 : 5
Simplified;
6 : 1