X=7 and x+1=8 are two consecutive integers.
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.
The best thing to do is to divide the amount she has driven (357.9) by the miles (21)
As you're looking for an estimate, you have to round them.
357.9 rounds to 360
21 rounds to 20
Therefore, you've got to divide them
360/20= 18
Therefore, Ellen has driven approximately 18 miles
Hope this helps :)
Answer:
3
Step-by-step explanation: