The graph shows that the amount of water in a person's body varies directly with the person's mass. What is the ratio of the vertical distance to the horizontal distance on the graph between the points (15, 10) and (30, 20) ?

Answer 1

(20 - 10) / (30 - 15)

Answer 2

Change in vertical distance = 20-10 = 10
change in horizontal distance = ....

now form the ratio:
change in vertical distance : change in horizontal distance
=