#include<iostream>
#include<string>
#include<algorithm>
using namespace std;
	
int F(int alpha,int beta,int ch){
	return (alpha*ch+beta)%26;
}
int gcd(int a,int b){
	return b==0?a:gcd(b,a%b);
}
int main(){
	int n;
	string in,s,ans;
	cin>>n;
	getline(cin,in);
	while(n--){
		getline(cin,in);
		for(int i=1;i<26;i++){
			if(gcd(26,i)!=1)continue;
			for(int j=0;j<26;j++){
				int table[26];
				for(int k=0;k<26;k++){
					table[F(i,j,k)] = k;
				}
				s.resize(in.size());
				for(int k=0;k<in.size();k++){
					if(in[k]==' ')s[k]=' ';
					else s[k] = table[in[k]-'a']+'a';
				}
				if(s.find("that",0)!=string::npos
					|| s.find("this",0)!=string::npos){
					cout<<s<<endl;
					goto BREAK;
				}
			}
		}
		BREAK:;
	}
	return 0;
}