For each pair of points, find the slope of the line that passes through both points. If you get stuck, try plotting the points on graph paper and drawing the line through them with a ruler

1. (1, 1) and (7, 5)

2. (1, 1) and (5, 7)

3. (2, 5) and (-1, 2)

4. (2, 5) and (-7, -4)