Given two dice are thrown

Possible outcomes =$6\times 6=36$

$\therefore$ The sample space

$S=\left\{\begin{array}{1 1}(1,1)(1,2)(1,3)(1,4)(1,5)(1,6)\\(2,1)(2,2)(2,3)(2,4)(2,5)(2,6)\\(3,1)(3,2)(3,3)(3,4)(3,5)(3,6)\\(4,1)(4,2)(4,3)(4,4)(4,5)(4,6)\\(5,1)(5,2)(5,3)(5,4)(5,5)(5,6)\\(6,1)(6,2)(6,3)(6,4)(6,5)(6,6)\end{array}\right\}$

B=Getting an odd number on first die

$\Rightarrow \left\{\begin{array}{1 1}(1,1),(1,2),(1,3),(1,4),(1,5),(1,6),\\(3,1),(3,2),(3,3),(3,4),(3,5),(3,6),\\(5,1),(5,2),(5,3),(5,4),(5,5),(5,6)\end{array}\right\}$

$\therefore$ not B=even number on first die.

$\Rightarrow \left\{\begin{array}{1 1}(2,1),(2,2),(2,3),(2,4),(2,5),(2,6),\\(4,1),(4,2),(4,3),(4,4),(4,5),(4,6),\\(6,1),(6,2),(6,3),(6,4),(6,5),(6,6)\end{array}\right\}$