X + 9/7 = 10
- 9/7 -9/7
___________
x = 8 2/7
21v + 8 - 12v - 7 + 3t - 1t = (combine like terms)
9v + 2t + 1 <==
The speed is the ratio between the distance and the time:

Data:
d=6343miles
t=9h

Then, the plane traveled at a speed of 704.77 miles per hour.
You can look for the number 16 on the x-axis. (bottom line) and put a finger there. Then, look for 19 on the y -axis (left line) and put a finger there. Trace your left finger to the right and your right hand up until they meet. That is (16,19)
D. 663 square meters is the anwser