The line does not represent a direct variation because it does not go through the origin.
Answer:
Step-by-step explanation:
Example Equation of an ellipse with horizontal major axis with center at (0,0):
x%5E2%2Fa%5E2%2By%5E2%2Fb%5E2=1
For given problem:
b=20
b^2=400
a=30
a^2=900
equation: x%5E2%2F900%2By%5E2%2F400=1
y%5E2%2F400=1-x%5E2%2F900
Let's assume that Kirby walks with a speed

for a time

, and that he runs with a speed

for a time

.
The total time available for Kirby to catch the train is:

and this must be equal to the sum of the two times t1 and t2:
The distance Kirby should cover is

and this should be equal to the sum of the distances covered by walking and by running:

So we have a system of 2 equations:


If we solve the system, we find:


So, Kirby needs to run at least for 8 minutes in order to catch the train.