Roman and his good buddy Andrew are both mechanics at a shop that does oil changes. They are in a friendly competition to see who can complete the most oil changes in one day. Roman has already finished 4 oil changes today, and can complete more at a rate of 1 oil change per hour. Andrew just came on shift, and can finish 2 oil changes every hour. Sometime during the day, the friends will be tied, with the same number of oil changes completed. How long will that take?
