Click the change value buttons until you get the colour you want. Then, click convert to see how many ml of cyan, yellow, magenta and black paint you need. You even get a preview of the colour!
If you want to make a printer, something like this will be useful. Thanks to Maximouse for his project which contained the code for the colour preview: https://scratch.mit.edu/projects/405409039/ Thanks to 3nhcolor.com for the formula converting RGB to CYMK (WARNING: 3nhcolor.com is a http web address which means it may not be secure). I use colour instead of color because I use the UK spellings.