Answer:
a/5
Step-by-step explanation:
You can choose a random number for a and see which is greater. For example, you can say a = 40.
That would mean a/5 = 8 and a/8 = 5. Since 8 is greater than 5, a/5 will always be greater.
The calculation for circumference is 2πr or 2 × π (pi=3.14) × radius of a circle
Since the diameter of this circle is 7cm, and the radius is half of the diameter, 7 ÷ 2 = 3.5
So, 2×3.14(π)×3.5=21.98
In solving this problem we can consider Earth to be a sphere. When we have a circle, then we can use this formula to find arc length:

Where:
L= arc length (in this problem it is disance we need to travel)
R = radius of circle (in this problem it is equal to a radius of Earth)
C = angle we need to pass
We are told that two cities lie halfway around the world. If we fly to west this means angle is 180°.
This gives an arc length of:

If we want to fly to north we need to go to 90° northern latidtude and then back to 17° latitude. This means angle is:
C=2*(90-17)=2*73°=146°
This gives an arc length of:

We can see that flying north is shorter. It is shorter by:
12440.71 miles - 10090.8 miles = 2349.91 miles