Two cars started from the same point, at 5 am, traveling in opposite directions at 40 and 50 mph respectively. At what time will they be 450 miles apart?	Choose the correct choice from the following
A) 9 am B) 10 am C) 6 am D) 8 am E) 7 am
After t hours the distances D1 and D2, in miles per hour, traveled by the two cars are given by   D1 = 40 t and D2 = 50 t   After t hours the distance D separating the two cars is given by   D = D1 + D2 = 40 t + 50 t = 90 t   Distance D will be equal to 450 miles when   D = 90 t = 450 miles   To find the time t for D to be 450 miles, solve the above equation for t to obtain   t = 5 hours.   5 am + 5 hours = 10 am   Answer 10 am
<result>B</result>
Two cars started from the same point, at 5 am, traveling in opposite directions at 40 and 50 mph respectively. At what time will they be 450 miles apart?