If I right understood, there are needed to translate it as a percentage. It’s not hard. For example: If 500 is 100%, then the 50% is 1/2 from 100%, I.e. 50% from 500 is will be 250, because, it’s 1/2 from all sum.
When calculating percentages, it is most convenient to first calculate 1 percent of the number. From 500 it will be 5%, because 100% of 100 is 1, and 500 divided by 100 will be 5. Just solve a little problem with percentages and you will solve it without thinking.