Hello!
To find the slope of the line given two points, you use the formula y2-y1/x2-x1. Each ordered pair can represent either the 1's or the 2's, and the slope will be the same. We will have (4,5) be (x1,y1) and (9,7) be (x2,y2). Now we will plug it into the equation.
7-5/9-4
2/5
Just to check, we will switch the ones and twos.
5-7/4-9
-2/-5
2/5
The slope of the line is 2/5.
I hope this helps!