#include<bits/stdc++.h>
using namespace std;
int main(){
    int t;
    cin>>t;
    while(t--){
        long long x,a,b;
        cin>>x>>a>>b;
        if(a*x>=b){
            cout<<x<<endl;
        }else{
            cout<<a*x-b<<endl;
        }
    }
    return 0;
}