Alan and Dave leave from the same point driving in opposite

Alan and Dave leave from the same point driving in opposite directions. Alan driving at 55 miles per hour and Dave at 65 mph. Alan has a one hour head start. How long will they be able to talk on their car phones if the phones have a 250 mile range?

Solution

55T+65(T-1)=250
55T+65T-65=250
120T=250+65
120T=315
T=315/120
T=2.625 HOURS AFTER ALLEN LEAVES THEY\'LL BE 250 MILES APART.