Algebra word problem, need help?

Question

A commuter bus takes 2 hrs to get to downtown. An express bus takes 45 min on the same route and travels 25 mph faster than the commuter bus. what is the speed of the commuter bus.

The book gives me an answer of 15 mph but I cant figure out how to get that answer. Can someone explain it for me please????

Answer 1

Remember that  Distance = Rate X Time

You can set up two equations here, one for the commuter bus, and one for the express bus.  You know the times for each one.   (Make sure you use minutes for both)  

You don't know the rate for the commuter bus.  This is your first unknown, let's call it r.  

You know the rate for the express bus now, sort of.   It's 25 mph faster than the commuter bus, right?   So make that (r+25).  

Now you have two equations.

Since the distance they travel is the same, you can set those equal to each other.  

Your single equation should now look like:

Commuter bus rate X Commuter bus time = Express bus rate X Express bus time.  

Plug the numbers in, do the simple algebra to solve for r  and the answer should appear to you.    Do lots of these problems and believe me, it will get easier.  Algebra is just about learning a new and really important way to think