Verified answer

R is the ideal gas constant, it's always going to be the same number but I'm not going to give you that number because it seems you're doing homework or something in which case you should be given that number as it's a constant it never changes so check your textbook and if you aren't doing homework then a simple google search for "ideal gas constant" will give you the number you need. It's just another one of those numbers you should probably memorize.