N level is pretty easy frm wad i heard frm my frens.... its not
tat tricky n basically wad u haf to do is kept on practising those
sums in the tys.....
If u r not sure how to tackle the harder sums , i suggest u go n
ask ur frens , if u dun understand wad they taught u , best is to
go n pester ur maths teacher.... or engage a gd tutor , someone u r
familiar wif... it helps.... 
