the number that must be added to each of the numbers 8,21,13 and 31 to make the ratio of the first two numbers equal to the ratio of last two numbers?

• (8+x)/(21+x)=(13+x)/(31+X)
  248+39x=X^2=273+34x+X^2
  5x=25
  x=5 ans
• 11 years agoHelpfull: Yes(14) No(0)
• it will be tested by simply options .....
  or by simply trail and error method....
  or by equation...
  5 will satisfy the equation as
  
  8+5....13+5
  ----=---------
  21+5....31+5
  
  1/2......
  
  
  
  
  or
  
  
  using equation...
  let x be the number to be added...
  
  (8+x)(31+x)=(21+x)(13+x)
  248+39x=34x+273
  x=5..
  
  
  
• 11 years agoHelpfull: Yes(3) No(2)
• let no. is x
  then from question
  8+x/21+x=13+x/31+x
  by solving x=5 ans.
• 11 years agoHelpfull: Yes(3) No(0)
• (8+x)/(21+x)=(13+x)/(31+x)
  solving above eq we get x = 5
• 11 years agoHelpfull: Yes(3) No(0)
• add a no=5
  we will get 13:26=1:2
  18:36=1:2
• 11 years agoHelpfull: Yes(1) No(2)