Answer:
Oil: 24 ml; Onion: 56 g; Potatoes: 0.36 kg; Milk: 0.44 l
Step-by-step explanation:
First, we see how much of the soup recipe he wants make.
4 portions out of 20 portions = 4/20 = 1/5 = 0.2
He wants to make 0.2 of the amount of the recipe.
Now we multiply every amount by 0.2
Oil: 0.2 * 120 ml = 24 ml
Onion: 0.2 * 280 g = 56 g
Potatoes: 0.2 * 1.8 kg = 0.36 kg
Milk: 0.2 * 2.2 l = 0.44 l