I'm planning on feeding Titan a half kibble half raw diet. I'll be feeding him N and D Quinoa Functional Skin and Coat Duck. The max size they have is 15.4 lbs. I'll be feeding him about 2 cups a day. 2 cups in morning and He will get raw at night( sometimes he'll get kibble At night so sometimes 4 cups a day) How many cups are there in that size bag and how long would it last?