The united states uses 24% of the worlds supply of energy. what fraction of the world energy is this?

Hi there!

We can start by making the fraction 24/100. 
To put this into lowest terms, we can divide both the numerator and the denominator by a common multiple. For instance, we could start with 2, since they both divide equally into 2. 
24/2=12
100/2=50
We end up with 12/50 - but we can divide both these numbers of 2 again! So we continue.

12/2=6
50/2=25
6/25 is your answer!

Hope this helps!