Kevin made a business trip of 312.5 miles. He averages 60 mph for the first part of the trip and 55 mph for the second part. If the trip took a 5.5 hours how long did he travel at each rate

Kevin travels for 2 hours at 60 mph and 3.5 hours at 55 mph

Step-by-step explanation:

Let's say that Kevin spends x hours going 60 mph and y hours going 55 mph. We can say that the sum of the two parts is 5.5, so x+y = 5.5 . Next, he goes 60 miles per hour for the first part of the trip, so for each hour he goes 60 mph, he travels 60 miles. We can then denote 60 * x as the distance traveled during the first part of his trip as he goes 60 mph for x hours. Similarly, 55 * y denotes the distance Kevin travels during the second part of his trip. His total distance is thus 60 * x + 55 * y = 312.5 miles

We have

x + y = 5.5

60 * x + 55 * y = 312.5

One way we can solve this is to solve for y in the first equation and plug that into the second. Subtracting x from both sides in the first equation, we get

y = 5.5 - x

Plugging that into the second equation, we get

60 * x + 55 * (5.5-x) = 312.5

60 * x + 55 * 5.5 - 55x = 312.5

5x  +302.5 = 312.5

subtract 302.5 from both sides to isolate the x and its coefficient

5x = 10

divide both sides by 5 to solve for x

x = 2

y = 5.5 - x = 5.5 - 2 = 3.5

Therefore, Kevin travels for 2 hours at 60 mph and 3.5 hours at 55 mph