Response:
Her brother catches up to her at 11 am + 4 hours = 15 p.m
Detailed explanation:
Provided information;
Ariel's speed = 45 mph
She departed at 9 a.m
Her brother's speed = 60 mph
He began at 11 a.m
Inferred from the question: Since Ariel's speed is 45 mph, after two hours she is ahead by 90 miles.
Meanwhile, her brother travels at 60 mph, hence he is traveling (60 - 45) = 15 mph faster
Therefore, with this speed, he will catch up to her in = 4 hours.
So her brother catches up with her at 11 am + 4 hours = 15 p.m