A16 oz. package of brown rice costs 79 cents and 32 oz. package of white rice costs $3.49. which package is a better deal?

If we were to pit it in y=mx+b then for the first pack it answer up to -1.77 as to the second pack it is -1.63 the one with better one would of been the second pack.
But if we were to just do it as y2-y1 and x2-x1, when solving this should be how it looks 3.49 - .79 which equals 2.7 and 32 - 16 which equals 16. . . But this wouldn't help so I think the second package is the correct one.

Distance=slopeslope is -2/4which equals-1/2the distance between these two points is -1/2