Please I need advise my DS did reasonably well in his science maths and humanity, now he thinks too easy he doesn't make much effort. I dont want to interfere too much but his attitude is worrying me at the same time.

Is he taking A levels now? If he only did reasonably well (as opposed to very well) at GCSE, maybe you are mistaking complacency for inability - or fear to try because he feels he can't do it?

What do the teachers say? If they feel he is doing well, what do you think he should be doing differently? If he is doing OK and wants some time at home to chill out - yes he will have to do some work at home but downtime is equally important.