#include<iostream>
#include<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<vector>
#include<cmath>
#include<cstdio>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define it ::iterator
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double ESP=1e-10;
using namespace std;
int main(){
  int n;
  cin>>n;
  rep(i,n){
    string s;
    string ans;
    bool han=false;
    if(i==0)getline(cin,s);
    getline(cin,s);
    rep(a,27){
      rep(b,27){
	string tmp=s;
	rep(j,tmp.size())if(isalpha(tmp[j]))tmp[j]=(a*(tmp[j]-'a')+b)%26+'a';
	rep(j,tmp.size()-3){
	  if(tmp.substr(j,4)=="this"){ans=tmp;han=true;}
	  if(tmp.substr(j,4)=="that"){ans=tmp;han=true;}
	}
	if(han==true)break;
      }
      if(han==true)break;
    }
    cout<<ans<<endl;
  }


}