Answer:
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
