Prompt

Make a percentage calculator. Make it a single HTML file that opens in a browser with nothing to install and no other files. Put the CSS and JavaScript inside it. Do not use image files or any external address; use emoji or letters if you need a symbol.

Give it three sections, with a discount off a price first:
- what is X percent of Y
- X is what percent of Y
- from X to Y, what is the change

Write each one as a sentence with the numbers as blanks inside it, so it reads like the question I was going to ask. The answer appears as I type.

Show the working in one short line under each answer, for example "40 of 200 is 20 percent because 40 divided by 200 is 0.2".

When you are done, check the change section handles a decrease and shows it as a decrease rather than a negative increase.