Afamily has a annual income of 30,600.of this 1/4 is spent for food ,1/5for housing 1/10 clothing 1/9 for saving 1/4 for taxes and the rest for other expenses .how much is spent for food

In order for the function to be linear, what must m be and why? m = 22 because the rate of change is 1. m = 20 because the rate of change is 3. m = 22 because the rate of change is -1. m = 20 because the rate of change is -3.