Leah likes to stretch 5 minutes for every 10 minutes of dancing. how many minutes should she stretch if she is doing a 50 minute dance class?

Let's set up a proportion.
5/10=?/50
We know that ten times 5 equals 50, so we can multiply the numerator, 5, by 5 to get our answer (what you do to the denominator, you must also do to the numerator).
5x5=25
The answer is 25,