Kathy left home to walk to the mall, walking quickly at a rate of 4 miles per hour. Her sister Abby left home 1 hour and rode her bike to the mall at a rate of 10 miles per hour. How long will it take Abby to catch up to Kathy? Will give brainless, pls answer ;-;

it will take Abby 4 hours to catch up to Kathy.

Explanation:
Kathy has a head start in her way to the mall while Abby has a hour delay. Meaning when Kathy is 2 hours into the walk (8 miles in) Abby will come in at 10 miles in ahead of her. 5 hours into the walk Abby will be at 40 miles, 6 hours into the walk for Kathy she’ll be at 40 miles.