In the past when VR was the main component of the exam (with the maths and English only being looked at for borderline candidates) I have been told that the cut-off point was somewhere around 88% for the VR paper. Also, I cannot be certain that this is a fact but DS1 came out of the exam last year saying there were 100 questions not the usual 85 he was used to practicing so he said he felt rushed for time at the end.
The English paper is creative writing, so the level of difficulty for that is hard to measure ( we all know how great state schools are in developing writing skills
, although most of the children will be in the same boat). Their maths is much more based on the KS2 national curriculum questions than the problem solving types found last week - so yes a child who is good at maths will find the maths easy. However, I have added a note of caution to DS2 that there are still 1000 other applicants for the exam willing to put the school down somewhere on their form so he should take care not to plunge through the paper making silly mistakes just because he finds it easier.