Is the second paragraph meant to throw you off??? Because the answer to the question does not rely on the information based from the second paragraph...
Anyway, we know that the turtle started from (0, 0) and moved to (10, 8). Let's assume that (0, 0) is (x1, y1), and that (10, 8) is (x2, y2) for the sake of calculations.
To find how far the turtle moved to the right (along the x-axis) we take x1 from x2:
x2 - x1 = 10 - 0
= 10 = x2
***this is the "run"
To find how far the turtle moved upwards (along the y-axis) we take y1 from y2:
y2 - y1 = 8 - 0
= 8 = y2
***this is the "rise"
Notice that when something moves away from the origin the distance it traveled along the x-axis and y-axis is the same as its final position (or coordinates to where it traveled to).
Therefore, the,
slope = rise / run
= x2 / y2
= 10 / 8
= 5 / 4 (preferable for use)
= 1.25
