Calculating the sum with for loop

[Rale]

I don't know what to do after this...
Can you help me little bit?

  int n, i, s;
    cout << "How much do you want to count the sum of?\n";
    cin >> n;
    
    for(i=0; i<n; i++){
        cin >> sum;
        //WHAT A HECK NOW?!?!
    }

If you enter n = 3
I want to calculate sum (10, 15, 20 and to print 10 + 15 + 20 = 45)

If you enter n = 4
I want to calculate sum (10, 12, 20, 39 and to print 10 + 12 + 20 + 39= 81 I think?) .. and so on.

[Oriol Serrabassa]

You did not specify if numbers are natural so I am assuming they are natural.
Also I recommend you to declare the variable i inside the loop like this:

for (int i = 0; i < n; i++)

#include <iostream>
using namespace std;

int main () {
    int n, i, x, sum;
    cout << "How much do you want to count the sum of?\n";
    cin >> n;
    for(i = 0; i < n; i++) {
        cin >> x;
        sum += x;
        if (i+1 != n) cout << x << " + ";
        else cout << x << " = " << sum << endl;
    }
}

[Rale]

ok @Oriol Serrabassa

i put sum = 0 and it worked
with sum;
the result of 12 + 12 it was 2868.. something
thank u, u helped me a lot! :D