how many ml is 50/1?

Any number over one is always itself.....

What does 50/1 mean ? You need to specify what units you wish to convert to ml, not leave us to guess.

As a wild guess, all I can think of is that "50/1" is supposed to represent 50 litres ( do you realise that the " 1 " is a figure one, not a letter " l " ? And what is the purpose of the " / " ?)

However, if my speculation is correct, then since one litre is 1000 ml, then 50 litres = 50 000 ml.

If I am wrong, then you will have to re-state the question in a way that can be understood.

If like for a two stroke motorbike

It will say for example 50/1

This basically meens that ther is 50ml of petrol to every ml of engine oil

50/1 ml = 50ml

50/1 ml
= 50 ml