Im trying to preform mathimatical functions on variables in c++ but cant seem to get it to work some advice? heres my code

#include <iostream>

using namespace std;

int main()
{
int thisisanumber = thisisanumber - 10; //int says that thisisanumber is an integer
//if the user try's to put a decimal the . will be ignored

cout<<"Please enter your age: ";
cin>> thisisanumber; //cin says that a value goes into thisisanumber the user
// a number the user must press enter
cin.ignore();//you type input into program it takes enter key don't need this
cout<<"Your age is: "<< thisisanumber <<"\n";
//you must seperate string literals(strings enclosed in quotation marks) and
//variables useing <<<<<<
cin.get();
}

The first line of code doesn't make sense. Try

int thisisanumber; //int says that thisisanumber is an integer

if you want the -10
int thisisanumber;
int newnumber = thisisanumber-10;

-CG