2. The independent random variables \(X\) and \(Y\) are such that \(\mathrm { E } ( X ) = 20 , \mathrm { E } ( Y ) = 10\), \(\operatorname { Var } ( X ) = 5\) and \(\operatorname { Var } ( Y ) = 4\). Find:
a. \(\mathrm { E } ( 2 X - Y )\)
b. \(\operatorname { Var } ( 2 X - Y )\)