Suppose you work for a large coffee distributor that has a secret coffee blend it sells to local stores. You mix the Kenya blend with the Arabian Mocha blend, but always in the same proportion. Yesterday, you mixed 90 pounds of the Kenya blend with 18 pounds of the Arabian Mocha blend. Today, there is 40 pounds of the Kenya coffee left in stock. How many pounds of the Arabian Mocha coffee should you mix with it to get your secret blend?