Height of the plant growth is given in a table, where it is in linear pattern,
 
Week \(1\) \(2\) \(3\) \(4\)
Height of the plant in \(cm\) 9 \(x\) 17 \(y\)
                                                                                     
Find the missing terms \(x\) and \(y\) and constant difference.
 
\(x = \)  
 
\(y = \)       
 
Constant difference \(=\)