D = rt

Yep you should.

Look, when Sarah meets her friends they have both traveled the same distance from Sarah's friends house Right? But Sarah has traveled this distance at 65mph in t hours and her friends covered it at 45mph in (t+1) hours.

& since that distance is D=65t and D=45(t+1)
then 65t=45(t+1)

Now you can solve for t which is the time in hours* it takes for Sarah to catch her friends.

Rap c∫;?/

Another sanity heck in word problems is to fit the units. In this case the two speeds are given in mph (miles/hour), the times in hours and distances in miles. BTW Sarah catches her friends at mile (65t) 146 ¼., which makes sane.

It will take Sarah 45 / (65 - 45) hours = 2hours and 15 minutes to overtake her friends, given the total trip time is at least this duration.

In other words she is gaining on them 20 miles every hour and her firends have a 1 hour head start so 65 * 2.25 = 45 * (2.25 + 1) = 146.25 miles

You can also do this one in parts. The friends are an hour ahead and going 45, so they are 45 miles ahead. Sarah is going 20 mph faster than they are, so you can use D = RT with D=45 and R=20. Of course, you still get the answers above.

hey
I want to thank all the tutors who took time to reply to my question. I am saving your notes and learning from them. Again, your help is very helpful.

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