There are three baskets, suppose $B1$, $B2$, $B3$
$B1$ contains $2x$ Apples
$B2$ contains $x$ Apples
$B3$ contains $(2x *3/4) =3*x/2$
according to question;
$( 2x + x + 3x/2 ) / 3 =30$
$(4x + 2x + 3x) / 6 = 30$
$9x=180$
$x=20$
Basket A contains $2x$ apples = $2 * 20 = 40$ Apples