How would you find the expected value?

Jessica Asked: How would you find the expected value?

OKay.
I reaaaallly need some help!
how would i calculate the expected value for this situation?

its 10 dollars to see the physic and figure out if youre having a boy or a girl.

the chance of having a boy is .52 and the chance for having a girl is .48

the psychic wants to know how much profit he'll make.
how do i do this?