Find the information gain by splitting the dataset using Age?

$\backslash$table$[[$#$,$Age,Prescription,Astigmatism,Rate,$\backslash$table$[[$Lenses$],[($Class$]]],[1,$Young,Myope,No$,$Reduced,None$],[2,$Young,Myope,Yes,Normal,Hard$],[3,$Young,Hypermetrope,No$,$Reduced,None$],[4,$Young,Hypermetrope,Yes,Reduced,None$],[5,$Young,Hypermetrope,Yes,Normal,Hard$],[6,$Young,Myope,No$,$Reduced,None$],[7,$Middle,Myope,Yes,Reduced,None$],[8,$Middle,Myope,Yes,Normal,Hard$],[9,$Middle,Hypermetrope,No$,$Normal,Soft$],[10,$Middle,Hypermetrope,Yes,Reduced,None$],[11,$Middle,Hypermetrope,Yes,Normal,None$],[12,$Middle,Myope,No$,$Reduced,None$],[13,$Middle,Myope,No$,$Normal,None$],[14,$Senior,Myope,Yes,Reduced,None$],[15,$Senior,Myope,Yes,Normal,Hard$],[16,$Senior,Hypermetrope,No$,$Reduced,None$],[17,$Senior,Hypermetrope,No$,$Normal,Soft$]]$