include[HTML_REMOVED]
include[HTML_REMOVED]
include[HTML_REMOVED]
include[HTML_REMOVED]
include[HTML_REMOVED]
using namespace std;
int N,M;
int exgcd(int a,int b,int &x,int &y){
if(b==0){
x = 1,y = 0;
return a;
}
int d = exgcd(b,a%b,x,y);
int tmp = x;
x = y;
y = tmp -a/b*y;
return d;
}
int main(){
int i,j,k;
cin>>N;
for(i = 1;i<=N;i++){
int a,b,m;
scanf("%d %d %d",&a,&b,&m);
int x,y;
int d = exgcd(a,m,x,y);
if(b%d==0){
int t = b/d;
printf("%d\n",((long long)x*t%(m/d)+(m/d))%(m/d));
}
else
printf("impossible\n");
}
return 0;
}