A certain chef is combining two mixtures to create a soup. If she combines a cups of one mixture that contains 5 percent butter with another mixture of b cups that contains 10 percent butter in order to make c cups of soup that contain 8 percent butter, and nothing else is added to the soup, what is the value of a ?

(1) b = 3

(2) 2c - 2a = 6


OA D

Source: Princeton Review