The correct response is:
Riley and Layla will each pay personal income tax on the portion of earnings that is theirs.
In a partnership, the partnership itself does not pay taxes on its earnings. Instead, the income "passes through" to the partners, who then report their respective shares of the income on their personal tax returns and pay taxes accordingly. So, in this case, Riley will pay taxes on 80% of the earnings, and Layla will pay taxes on 20% of the earnings.