One rose is 50 cents, so 2 roses cost $1 ( 50 cents x 2).
2 roses per dollar x 20 dollars = 40 total roses sold.
When they sell $20 dollars they make $6, so that means they pay 20-6 = $14 dollars for the 40 roses.
$14 / 40 roses = 0.35 per rose.
She pays 35 cents per rose.
