Lester leaves school to walk home. His friend, Braelin, notices 0.25 hours later that Lester forgot his phone at the school. So Braelin rides her bike to catch up to Lester and give him the phone. If Lester walks at 4.3 mph and Braelin rides her bike at 8.5 mph, find how long (in hours) she will have to ride her bike until she catches up to him.

Round your answer to 3 places after the decimal point (if necessary) and do NOT type any units (such as "hours") in the answer box.