can someone please tell me where am I wrong?

Question

script:
#include <iostream>
using namespace std;
int main()
{
int a1;
int d;
int n;
int an;

cout << "what is a1?" << endl;
cin >> a1;

cout << "what is d?" << endl;
cin >> d;

cout << "what is n?" << endl;
cin >> n;

cout << "what is an?" << endl;
cin >> an;

if (a1 =999){
int x = an - d * ( n - 1 ) ;
cout << "a1 = " << x <<endl;
}

if (d = 999){
int x = ( an -a1 ) / ( n - 1 ) ;
cout << "d = " << x <<endl;
}

if (n= 999){
int x = ( an - a1 + d ) / d ;
cout << "n = " << x<<endl;
}

if (an =999) {
int x = a1 + ( n - 1 ) * d ;
cout << "an = " << x << endl;
}

return 0;
}

Answer 1

You are using = (assignment operator) instead of == (equality testing operator) for your if conditions.