A farmer has 90 acres available for planting corn and soybeans. The cost of seed per acre is
$\$ 4$ for corn and $\$ 6$ for soybeans. To harvest the crops, the farmer will need to hire some temporary help. It will cost the farmer $\$ 20$ per acre to harvest the corn and $\$ 10$ per acre to harvest the soybeans. The farmer has $\$ 480$ available for seed and $\$ 1400$ available for labor. His profit is $\$ 120$ per acre of corn and $\$ 150$ per acre of soybeans. How many acres of each crop should the farmer plant to maximize the profit?