This is a basic web application for Path of Exile players that calculates the lowest possible combination of items in order to reach the 40% quality item threshold vendor recipe.
To use the application, hover over an item in game (make sure the game is focused) and press CTRL+C to copy its data. Then go to the application's page (making sure it is focused) and press CTRL+V to paste the data. Do this for all of your quality items of the same type (e.g. flask), and if a combination is possible, it will highlight the items to use in green. If you have a lot of items pasted, you can click "Remove Combination" to remove the current combination's items and see if any other combinations are possible.