A number when divided by D leaves a remainder of 8 and when divided by 3D leaves a remainder of 21. What is the remainder left, when twice the number is divided by 3D?
a) 13 b) cannot be determined c) 3 d) 42

• x/d=8 and x/3d=21
  3x/3d=24
  (3x/3d)-(x/3d)=(24-21)=3
• 13 years agoHelpfull: Yes(22) No(12)
• let no be "a"..
  a=Dx+8--------1
  a=3Dy+21------2
  
  D(x-3y)=13
  .
  . .x=4,y=1 nd D=13
  sub D nd X in 1 thn a=60
  twice-->2a=120
  120 divided by 3D (13x 3)
  120/39==> 3 ans
• 13 years agoHelpfull: Yes(9) No(2)
• hey avinesh
  x/d=8 means 8d=x its not give remainder
  let the number be n so
  n=Dx+8 ( x is quotient) ----1
  n=3Dy+21(y is quotient) ----2
  ->D(x-3y)=13
  so As 13 is prime number
  there are two option D=1 and x-3y=13 or d=13 and x-3y=1
  d is not = 1 as it give remainder
  so D=13
  x-3y=1
  now we 1 is n=Dx+8
  let x=4 and y=1
  then from 1 n=60
  when 60 divide by 13 give remainder 8
  and when 60 divide by 39 give remainder 21
  when 2n=120 divide by 3D=39 remainder= 3
• 13 years agoHelpfull: Yes(7) No(0)
• option-c
  solution
  
• 13 years agoHelpfull: Yes(0) No(5)
• c)3 is ans
• 13 years agoHelpfull: Yes(0) No(4)