We have two responses for you

Tamara,

You can do unit conversions using tables, a scientific calculator, or even Google: enter

[45 km/minute in miles per minute]

Once you have the answer in miles per minute, your problem is :

At (some number of) miles per minute how long does it take to make 50 miles?

You should should be able to solve directly, perhaps using a calculator. If you still find it tricky set up a parallel problem with very easy numbers of similar proportions (but don't use 1):

At 2 miles per minute how long does it take to make 6 miles?

Well, that was easy! Now, did you multiply or divide, and if you divided what did you divide? Now do the same with the real problem.

Good Hunting!
-RD

Hi Tamara.

Google keeps getting smarter.
Try typing 50 miles divided by 45 kilometers per minute into Google.

Cheers,
Stephen.