Answer:
EF, where E is at (1, 9) and F is at (2, 5)
Explanation:
Slope = rise/run or y/x. In a coordinate, a point on a graph is represented as (x,y). When the slope is -4 (or -4/1), this means the y value will decrease (as it is negative) by 4 units, while the x value increases (as it is positive) by 1 unit. The line EF demonstrates the values (1, 9) and (2, 5). The difference between them is (1, -4) in (x, y) form.