The currency in France, and 14 other European countries as Germany, Spain and Italy, is the Euro. See
http://www.parisdigest.com/information/euro_converter.htm for the exchange rate. There are many restaurants for French working people where they serve menus at below 15 euros, but you won’t find them in touristic areas. Chinese restaurants are quite cheap. You can get a quite good French meal for 30 euros. It can also be much more expensive in touristic areas and at gastronomic restaurants. You really have to look around. You can give tips of two euros although you don’t have too. Have a great time in Paris.