You should have been given your marks for each assessment task and the weighting of the tasks so it isn't hard to work it out e.g.
task 1 - 18/20 - weighting 15% = 13.5/15
task 2 - 24/30 - weighting 20% = 16/20
task 3 - 28/30 - weighting 25% = 23.3/25
task 3 - 86/100 - weighting 40% = 34.4/40
Now add them up - raw assessment mark would be 87.2 which school would probably send in the BoS as 87. Could be ranked anywhere from 1st to last with a mark like that depending on everyone else's marks.
However schools are able to 'adjust' marks so long as they do it to the entire cohort e.g. add 5 marks, or put on a bell curve or something like that - mine tends not to do so but others do.