#include<cstdio>

using namespace std;
typedef long long ll;

ll exgcd(ll a,ll b,ll &x,ll &y)
{
    if(!b)
    {
        x=1,y=0;
        return a;
    }
    ll ret=exgcd(b,a%b,y,x);
    y-=a/b*x;
    return ret;
}

int main()
{
    ll a,b,x,y,m;
    int n;
    scanf("%d",&n);
    while(n--)
    {
        scanf("%lld%lld%lld",&a,&b,&m);
        ll d=exgcd(a,m,x,y);
        int mod=m/d;
        if(b%d)
            puts("impossible");
        else
            printf("%lld\n",(x*b/d%mod));
    }
    return 0;
}