How can i get my cat to eat her food?

My mother bought cheap generic bran food. My cat refuses to eat it and will eat the dog food instead. We tried mixing the dog food with the cat food, but she just picks out the dog food and leaves the rest of the cat food. I dont want to throw away a big bag of cat food. How can I get my cat to eat the cheap food? Should I just give it to my dogs so it doenst get wasted?