Help me in solving GYMDAY problem

help
,
1

My issue

whats wrong with my solution ?

My code

#include <bits/stdc++.h>

#define ll long long
#define mod 1000000007
using namespace std;

int main() {
    int t;
    cin >> t;
    while (t--) {
        double discount, membership_cost, budget;
        cin >> discount >> membership_cost >> budget;

        double x = membership_cost;
        int sessions = 0;
        double possibility = (x -= x*((discount*budget)/100)); // checks whether the membership cost is higher then 0 even when budget is exhausted
        x=membership_cost;

        while (membership_cost>budget) {
            if(possibility>0){
            sessions=-1;
            break;
        }
            sessions++;
            budget--;
            x -= x*(discount/100);
            if(x<=budget){
                break;
            }
            else{
                x=membership_cost;
                discount+=discount;
            }
        }
        cout << sessions << endl;
    }
    return 0;
}

Problem Link: International Gym Day Practice Coding Problem