Bank Math Master১টি পরীক্ষায় এসেছেপ্রশ্ন ১৯A is two years older than B who is twice as old as C. If the average of the ages of A, B and C be 9, the how old is B? কক) 8 yearsখখ) 10 yearsগগ) 12 yearsঘঘ) 18 yearsউত্তর দেখুন