Answer:
40 minutes
Step-by-step explanation:
She starts running 20 minutes after, meaning the first one is already two miles ahead.
30 minutes goes by one is at 3 miles and the other is at 2 miles
40 minutes go by and one is a 4 miles and the other is at 4 miles
because of the 20 minutes, it'll take 40 minutes for them to meet each other
