#include <iostream>
#include <string>
using namespace std;

int func(int a, int b, int c)
{
	return (a * c + b) % 26;
}

int main(void)
{
	int n;
	string a;
	getline(cin, a);
	
	n = atoi(a.c_str());
	for (int i = 0; i < n; i++){
		// cout << "*" << endl;
		string str;
		getline(cin, str);
		
		for (int a = 0; a < 100; a++){
			for (int b = 0; b < 100; b++){
				string tmp = str;
				for (int j = 0; j < str.size(); j++){
						if (tmp[j] == '.') continue;
						if (tmp[j] == ' ') continue;
						if (isdigit(tmp[j])) continue;
						tmp[j] = func(a, b, str[j] - 'a') + 'a';
				}
				
				if (tmp.find("that") != string::npos || tmp.find("this") != string::npos){
					cout << tmp << endl;
					goto a;
				}
			}
		}
	}
	
	a:;
	return 0;
}