For A B and C, you just plug in the given number
A

B

C

And for D, you set the equation to 26 and solve for n

I had to use x instead of n, but for D n=7. :)
All you have to do is divide the number of miles by the time.
420/8
52.5 miles per hour rounds up to
at least 53 miles per hour
Answer: 20
Step-by-step explanation: because 3+17=20
#19 is B:100 and #20 is H:30 I believe, if those were the answers you were looking for :)