Laila drives to the station each day to pick up her husband Majnu, who usually arrives on a train 6'o clock. Last Monday, Majnu finished his work earlier, caught an earlier train and arrived at the the station 5'o clock. He started to walk towards home and eventually met Laila who drove him rest of the way, getting home 20 minutes earlier than the usual. On Tuesday, he again finished early and found himself at the station at 5:30. Again he began to walk home, again he met Laila on the way and she drove him rest of the way, Assume constant speed throughout no wasted time for waiting. How earlier than the usual time were they home on tuesday