Three years ago the average age of A & B was 18 years. With C joining them now, the average age becomes 22 years. How old is she?

• u mean to say C?
  
  present average age of A and B =18+3=21
  
  so c's present age=22+(22-21)*2=24 years
• 10 years agoHelpfull: Yes(2) No(0)
• let age of A be = x years
  age of B = y years
  Three years ago A = x-3 years
  similarly three years ago B = y-3
  avg age of A+B/2= (x-3+y-3)/2 = 18 ==> x+y = 42 years
  After joining of C avg of A,B,C = (A+B+C)/3 = (42+C) =22*3==? C=24 YEARS OLD
  
• 10 years agoHelpfull: Yes(1) No(0)
• present age of A & B is =(18*2)+6=42;
  after joining of c,
  present age of A,B & C is=22*3=66;
  so age of C is=66-42=24.
• 10 years agoHelpfull: Yes(1) No(0)
• (A-3)+(B-3)/2=18
  A+B=30-----(1)
  NOW
  A+B+C/32=22
  30+C=66 [FROM (1)]
  C=36(ANS)
  
  
• 10 years agoHelpfull: Yes(0) No(2)