How do you figure out a percentage

Let x represent the percent you need: x/100 * 5/20. then cross multiply. 20x = 500. then divide both sides by 20. x = 500/20 = x = 25. if you have a decimal and you wish to convert it to a percent all you need to do is multiply by 100 and put a percent sign on the end. so,.002 * 100 =.2%