PHP Counting the Vowels in a String

I'm trying to learn more about PHP for class and I came across this sample that I am trying to figure out. I need to create an array of 5 Strings that can be words and or phrases. The code needs to be able to determine the number of vowels in each string and have them displayed

Example:

a nut for a jar of tuna: 8

OR

8: a nut for a jar of tuna

It only has to be hard coded in PHP but I don't mind if it includes the HTML component just so I can see how it all fits together.

Thank you so much!