Answer:
X= 53
Random comment:
Hopefully i've helped you good luck.
21 is 25% of 84
21 • 4 = 84
You can check this answer by take 25% of 84.
84 • 0.25 = 21
I have absolutely no clue how mile markers work, but assuming they mark a single mile each, his sister will either be five miles in front, or five miles behind him.
The possible answers are mile markers 8 and 18.
