Answers:
- 24 mL of oil
 - 60 g onions
 - 0.36 kg potatoes
 - 0.4025 cup of milk
 
The units for the milk weren't stated, but I'm assuming it's probably "cups".
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Step-by-step explanation:
The recipe makes 16 portions or servings of soup. Richard only wants 4 servings. This means he needs to divide each ingredient amount by 4. Note how 16/4 = 4.
So,
- 96/4 = 24 mL of oil is needed
 - 240/4 = 60 grams of onions are needed
 - 1.44/4 = 0.36 kilograms of potatoes are needed
 - 1.61/4 = 0.4025 cups of milk are needed
 
Change "cups" to whatever other measurement unit is provided.