Half Popped Popcorn What Is The Equation For This Rule? "A Half-cup Of Unpopped Popcorn Is Needed To Make 6 Cups Of Popped Popcorn?

What is the equation for this rule? "A half-cup of unpopped popcorn is needed to make 6 cups of popped popcorn? - half popped popcorn

The rule reads: "A half cup of Unpopped popcorn is necessary to make 6 cups of popcorn. How can I write this as an equation? You can use variables in the letter, but please explain what they mean. :-) Thank you !