Each morning during the week, Joe's wife, Beatrice, drops Joe off at the commuter train station, She also picks him up at the station when he returns in the evening. One day, Joe leaves work earlier takes the train, and arrrives one hour before his wife gets there to pck him up. Joe decides that rather than waiting, he will walk towards home. As it happens, Bea spots Joe walking on the road and they head for home. At the moment they pull into the drive, Joe looks at his watch and notices that he has actually arrived home 20 minutes earlier than usual.
How long did Joe walk
d1=bea distance
d2=joe distance
r1=bea drive
r2=joe walk
t=time
so d2=(r1t)+(r2t)-d1
overall distance(D)=(r1+r2)2t