aa=2*ba+a (proba impartirii cu rest)
aa=10*a+a => 10*a+a=2(b*10+a)+a
11a=20b+2a+a => 8a=20b => a=20b/8
Ne trebuie fractia aa supra ba
aa=20b*10/8+20b/8=220b/8
ba=10b+20b/8=80b/8+20b/8=100b/8
aa/ba=(220b/8)(100b/8)=220b/8*8/100b (8 si b se simplifica)
aa/ba=220/100=2,2