#include<iostream>
#include<iomanip>
#include<algorithm>
#include<array>
#include<bitset>
#include<cassert>
#include<cctype>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<numeric>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=(n)-1;i>=0;i--)
#define ALL(a) (a).begin(),(a).end()
#define DUMP(o) {cerr<<#o<<" "<<o<<endl;}
#define DUMPC(o) {cerr<<#o; for(auto &e:(o))cerr<<" "<<e;cerr<<endl;}
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
const int MOD = 1e9 + 7;

//?????§??¬?´???°
int gcd(int x, int y) {
	return y ? gcd(y, x%y) : x;
}

signed main() {
	int n; cin >> n; cin.ignore();
	REP(i, n) {
		string S; getline(cin, S);
		REP(a, 26) {
			if (gcd(a, 26) != 1)continue;
			REP(b, 26) {
				string T = S;
				REP(j, S.size()) {
					if (S[j] == ' ') {
						continue;
					}
					int c = S[j] - 'a';
					c = (a*c + b) % 26;
					T[j] = char(c + 'a');
				}
				if (T.find("that") == string::npos&&T.find("this") == string::npos) {
					continue;
				}
				else {
					cout << T << endl;
					a = b = 26;
				}
			}
		}
	}
	return 0;
}