Answer
Answer may vary.
One possible example:
For every 60 seconds that pass, 1 minute passes.
$y = x/60$
Where x is how many seconds pass, and y is how many minutes pass.
Work Step by Step
There are an infinite amount of answers to this question since it is open-ended. I will explain step-by-step how to make an answer to this question.
Step 1: Think of a real-world situation. It would be preferred if there is a pattern that is linear. Describe it using words.
Step 2: Write an equation, and define the variables. Your equation, if there is a linear pattern, should look like this
$y = mx + b$
You should also define what x represents and what y respresents.
"Where x represents ____ and y represents ____" is a good sample outline.
Look at the Answer for a sample solution.