#include <bits/stdc++.h>

#define SIZE 300005
#define MOD 1000000007LL
#define INF INT_MAX / 3
#define LLINF 1LL << 60
#define REP(i,n) for(int i=0;i<n;i++)
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define DOWN(i,b,a) for(int i=b;i>=a;i--)
#define SET(a,c) memset(a,c,sizeof a)
#define FORALL(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define FOREACH(i,c) for(auto (i) : (c))
#define BIT(i,j) ((i)>>(j))&1
#define ALL(o) (o).begin(), (o).end()
#define ERASE(o) (o).erase(unique((o).begin(),(o).end()), (o).end())
#define SQ(x) ((x)*(x))
using namespace std;
typedef long long ll;
typedef valarray<int> Array;
typedef pair<ll,ll> Pll;
typedef pair<int, int> Pii;
typedef pair<double, double> Pdd;
template<typename T> inline void priv(vector<T>a){REP(i,a.size()){cout<<a[i];if(i==a.size()-1)cout<<endl;else cout<<" ";}}
int gcd(int a,int b){int c=max(a,b);int d=min(a,b);return c==0||d==0?c:gcd(c%d,d);}
int lcm(int a,int b){return a==0||b==0?0:a*b/gcd(a,b);}


void solve(string s)
{
  int a = 0, b = 0;
  for(int i = 0; i < s.size();)
  {
    int l = 0;
    bool f = false;
    while(i+l < s.size()&&s[i+l] != 0x20) l++;
    if(l != 4) i += l+1;
    else
    {
      string t = "";
      REP(j,4) t += s[i+j];
      FOR(v,1,25)
      {
        if(gcd(v,26)!=1) continue;
        FOR(w,0,25)
        {
          string tmp = t;
          REP(j,4) tmp[j] = 'a'+((v*(t[j]-'a')+w)%26);
          if(tmp == "this" || tmp == "that")
          {
            a = v; b = w; f = true;
            break;
          }
        }
        if(f) break;
      }
    }
    if(f) break;
    i += l+1;
  }
  REP(i,s.size()) if(s[i] != 0x20)s[i] = 'a'+((a*(s[i]-'a')+b)%26);
  cout << s << "\n";
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  int n; cin >> n; cin.ignore();
  REP(i,n)
  {
    string s;
    getline(cin,s);
    solve(s);
  }
  return 0;
}