Alcohol content with out the OG?

[unifx26]

Hi there, I am New at this and found the Hydrometer very hard to understand, I am attempting the Birdwatchers Sugar wash cut down to around 25 lts so my ingredients were 6kg of sugar, 1 lemon juiced, around 230g of tomato paste and rest distilled water at a temp of 30 cel then i tried to take a reading with a hydrometer but i forgot it is suposed to be at like 60 fahrenheit correct? before checking the OG?

well i checked it at 30c and it was around the 8.2 mark and was in a rush so just thought screw it there must be a way to tell the alcohol content afterwards with out this hydrometer, (wish i didn't now...)

is there a way I can come back from this? (to be honest i still dont quite understand the whole hydrometer reasoning)

I realise how stupid I must sound..

Thanks for your help in advance.
Michael.