2. The mass of carbohydrate is 400*40%= 160 (g)

Therefore, the total mass of protein and minerals is 400-20- 160=220 (g).

Protein is four times that of minerals, so the mass of protein is 220*4/5= 176 (g).

3. The total mass of protein plus carbohydrates = 400 * 85% = 340g.

Let protein be x and carbohydrate be y.

Then x+y = 340.

And satisfy X+X/4+Y+20=400.

Get x = 160y.

So the maximum is 180g.