What is the slope of the line ax + by = c? Find an equation for the line through the origin that is parallel. A) The slope is -a/b, and an equation for the parallel line is y = -a/bx. B) The slope is -b/a, and an equation for the parallel line is y = -b/ax C) The slope is a/b, and an equation for the parallel line is y = a/bx . D) The slope is b/a, and an equation for the parallel line is y = b/ax .