The function from \(A\) \(=\) \(\{\)4, 6, 12, 13\(\}\) to \(B\) \(=\) \(\{\)\(23\), \(7\), \(25\), \(11\)\(\}\)  is represented by the table below, where \(f(x)\) \(=\) \(2x\) \(-\) \(1\).
 
\(x\)
4
6
12
13
\(y\)
\(a\)
\(11\)
\(b\)
\(25\)
 
Find the values of \(a\) and \(b\).
 
\(a\) \(=\)
 
\(b\) \(=\)