1) 4(6j+1+8j) = 16j + 4 + 32j
2) 16j + 4 + 32j = 48j + 4
Maybe you meant solve for x?
If so, the answer is 4
The straight line is perpendicular to y = -3x + 4.
Therefore, the gradient of the straight line must be 3.
The equation of the straight line is y = 3x + 2.
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