Answer:
X is 39
Step-by-step explanation:
Explanation in picture above
Answer:

Step-by-step explanation:
Divide both sides by the numeric factor on the left side, then solve.

So Julia... 6 miles in 30 minutes. Let's find out how much she travelled in 1 hour. Multiply it by 2, since 30 x 2 = 60 mins = 1 hour, you get 12 miles per hour for Julia.
For Alex... 2 miles in 12 minutes. Multiply it by 5, as 12 x 5 = 60 mins = 1 hour, you get 10 miles per hour for Alex.
Julia travelled faster. She travelled 12 miles per hour while Alex travelled 10 miles per hour.