R中的最优化:最大化和最小化多个变量

I have a dataset with 70 foods and information about each food's nutritional value (protein/oz., fat/oz., cals/oz., etc.), as well as the food's cost/oz. I am trying to figure out--given a set budget in $--what the best combination of foods (and the amt. of each food) would be to maximize protein, minimize fat, minimize calories, etc. I aim to do this across a series of price points, and to plot each.I have a dataset with 70 foods and information