Math

[Qochata]

On a255-mile trip,Gary Alessandrini traveled at an average speed of 70 mph, got a speeding ticket, and then traveled at 60 mph for the remainder of the trip.If the entire trip was 4.5 hours and the speeding ticket stop took 30 minutes.how long did gary speed before getting stopped?  

[charly]

The speeding ticket took half an hour, so travel time was 4 hours.

At 70 mph he would have gone 280 miles.

Since he travelled some at 60 mph, it must have been far enough to change that 280 miles down to a 255 miles.

Since 60 mph is 10 mph slower than 70 mph and 255 miles is 25 shorter than 280, 25/10 = 2.5, so he travelled 2.5 hours at 60 and 1.5 hours at 70.  The total distance would be(2.5)60 +(1.5)70 =

150 + 105 = 255, and that's what we were given.