Assumption: The question should read "What is 300ml as a percentage of 6.5 ltr"
I am assuming that it is 300 ml and not 0.3 ml. The two zeros after the three do not make sense if it is 0.3ml as it is not normally written that way.
We need to make the units of measurement the same to enable direct comparison. I choose to use millilitres for everything. So we need to change 6.6 litres into millilitres
Using ratio in fractional form:
Multiply both sides by
300 ml to 6.5 litres is the same as 300 ml to 6500 millilitres
As a fraction this is:
Comparing this to percentage we have