Answer:
equation 1: 60*(x-3.5)=22.5*x to solve for x
equation 2: x+(x-3.5) to solve for hours
[answer at the bottom if you need it]
Step-by-step explanation:
Let's think about it in terms of x.
Suppose x hrs is the time it takes to get BACK. So the time to get there is (x-3.5) hrs.
60mph can be written as 60mi/hr. 22.5mph can be written as 22.5mi/hr.
You know that the distance there and back should be the same because Dan is going to the lake and back. To find distance of each trip, you have to multiply speed and time.
Distance TO: 60mi/hr * (x-3.5)hr
Distance BACK: 22.5mi/hr * x hr
The hr units cancel out to leave mi (miles, unit for distance)
Since the distance there and back are the same, you can set the distances equal to each other and solve for x.
60*(x-3.5)=22.5*x
That's not it though. Solving for x only gives you what x is, which is the time it takes to get back. The total time that the trip takes is x+(x-3.5), which is the time it takes to get there and come back from the lake.
Answer:
x= 5.6
x+(x-3.5) = 5.6+(5.6-3.5) = 5.6+2.1 = 7.7 hours total
Hope this was helpful!
