The high school asked Amanda to paint a few murals around the school. Her mural in the cafeteria will show a ray of sunlight breaking through storm clouds. To create the perfect gray paint for storm clouds, Amanda models the proportional relationship between the number of cans of black paint, x, and the number of cans of white paint, y, with the equation y = 2x. If Amanda used 5 cans of white paint, how many cans of black paint did she use?