pri 5 tough question

• syncopation_music

  27 Sep 08, 00:12

  Can anyone help me with this p5 maths question

  thanks in advance !!!

   

  

• FirePig

  27 Sep 08, 00:29

  cross multiply

• maurizio13

  28 Sep 08, 07:19

   

  I don't think primary 5 has algebra, but it's the only way I know how to solve it.

   

  Let the total number of stamps Malvin and Ken had be X.

  Initially:

  (2/5)X : (3/5)X

   

  Malvin bought 8 stamps and Ken lost 5 stamps:

  (2/5)X + 8 : (3/5)X - 5

   

  Malvin has 4/5 as many stamps as Ken:

   

  { (2/5)X + 8 - [ (3/5)X - 5 ] } / [ (3/5)X - 5 ] = 4/5

   

  [ -(1/5)X + 13 ] / [ (3/5)X - 5 ] = 4/5

   

  5 [ -(1/5)X + 13 ] = 4 [ (3/5)X - 5 ]

   

  -X + 65 = (12/5)X - 20

   

  X = 25

   

• eagle

  28 Sep 08, 09:19

  isn't total = 150?

  so that initial is 60:90
  then +8 and -5
  68 : 85 => 4:5

• maurizio13

  28 Sep 08, 09:41

   

  I interpreted the 4/5 as many stamps as Ken to be 80% more stamps as Ken.

   

  *shrugs*

   

   

• baiyun

  28 Sep 08, 10:56

  

• maurizio13

  28 Sep 08, 14:07

   

  If 4/5 means 4:5 then,

   

  Let X be the initial total and Y be the final total.

   

  (2/5)X + 8 = (4/9)Y --------(1)

  (3/5)X - 5 = (5/9)Y ---------(2)

   

  Solve for X and Y.

  X = 150

  Y = 153

   

  Don't know how to use diagrams like that to solve, was never taught the technique.

   

• FirePig

  3 Oct 08, 23:26

  Originally posted by maurizio13:

   

  If 4/5 means 4:5 then,

   

  Let X be the initial total and Y be the final total.

   

  (2/5)X + 8 = (4/9)Y --------(1)

  (3/5)X - 5 = (5/9)Y ---------(2)

   

  Solve for X and Y.

  X = 150

  Y = 153

   

  Don't know how to use diagrams like that to solve, was never taught the technique.

   

  Pls la...no ifs la. You dont understand simple english is it?