Answer:
20 millilitres of oil
Explanation:
You need to first find how much goes into 1 litre of oil and to do that we divide the two numbers
80/2 = 40
Now we know that for every 1 litre we need 40 millitres
Since .5 is half of 1 we just need to take half of 40
half of 40 = 20
20 millilitres of oil