Answer:
The answer to your question is below
Step-by-step explanation:
Data
Center = (0, 0)
Vertex = (13, 0)
Focus = (12, 0)
Process
From the data we know that it is a horizontal ellipse.
1.- Calculate "a", the distance from the center to the vertex.
a = 13
2.- Calculate "c", the distance from the center to the focus
c = 12
3.- Calculate b
Use the Pythagorean theorem to find it
a² = b² + c²
-Solve for b
b² = a² - c²
-Substitution
b² = 13² - 12²
-Simplification
b² = 169 - 144
b² = 25
b = 5
4.- Find the equation of the ellipse
or 
You can reword the two equations as:
-5x-y=15 (Divide original value by 3)
-2x+6y=6
Then use elimination to find x:
-30x-6y=90 (Multiply by 6 to get y values to be same to cancel out)
-2x+6y=6
You're left with:
-32x=96. Which can then be solved to find x which is -3.
Then plug back in
-2x+6y=6
Now to: -2(-3)+6y=6.
Which reduces to 6+6y=6. So y=0.
To graph them, just reword the equations (yes once again) so that y is in front.
y=-5x-15 and y=(1/3)x+1
I don't really get what the "35,000 feet university sea level" part is saying, but without it, the answer would be:
3.5 x 550 = 1,925
The plane traveled 1,925 miles.
And with it, the answer would be:
3.5 x 550 = 1,925
35,000 ft = 6.6 mi
1,925 + 6.6 = 1,931.6
The plane traveled 1,931.6 miles.
Hope this helped a little at least.