The answer is c. The range fo the length of the fish caught by Freddy is greater than the range of the length of the fish caught by Waldo.
Slope = 
So taking 2 points (0,0) and (60,120)
we have slope = (120-0)/(60-0) = 120/60 = 2
general equation of linear graph is y=mx+b with m be the slope
so y=2x+b
Now to find b, just plug any point of the graph in, such as (0,0)
so we get something like 0=2(0) + b => b=0
So your equation is y=2x
360=24%0f x
360=24/100*x
360*100=24x
36000/24=x
therefore, x=1500......
You need to find a number that all three of those numbers go into. They all go into 60. Then, divide 60 by three because there are three items. 60 divided by 3 is 20, which is the answer.