Calculate expected car-wash earnings

Let $X$ be the number of cars passing through a car wash between 4:00 pm and 5:00 pm on a sunny Friday, with probability distribution

$x$	4	5	6	7	8	9
$P(X=x)$	$1/12$	$1/12$	$1/4$	$1/4$	$1/6$	$1/6$

The manager pays the attendant $Y=2X-1$ dollars. Find the attendant’s expected earnings for this time period.