when a mom her baby and her infant stands on weighing machine and found to be 78 kg. And the combined weight of baby and her weight is 40kg more than her mother. And infant weight is 20% less than daughter then what is the weight of daughter??????

• let x be the wt of infant y be the wt of mother and z be the wt of daughter
  x+y+z=78 kg
  x+z=40+y
  x=z-(20/100)z or x=(80/100)z
  by solving 3rd eqn we get
  x=(4/5)z
  sub this in 2nd eqn
  y=(9z/5)-40
  sub in 1st eqn
  18Z=590
  z=32.78 kg
• 10 years agoHelpfull: Yes(14) No(0)
• let mother wt be m,daughter wt be d,infant wt be i
  then
  m+d+i=78
  d+i=m+40
  i=d-(20*d)/100
  i=80d/100
  from solving eq 1 &2
  m=19 kg
  from eq 2 & 3
  d=32.78kg
• 10 years agoHelpfull: Yes(2) No(0)
• x+y+z=78
  x+y=40
  so,z=(78-40)=38
  y=daughter's weight=38*(120/100)=45.60kg
• 10 years agoHelpfull: Yes(1) No(1)
• let x be wt of mother
  let y be wt of daughter
  let z be wt of infant
  now x+y+z=78
  y+z=40+x
  z=y-(0.2y)=>0.8y
  putting value of z in
  y+z=40+x
  1.8y-40=x
  now putting values of x and z in x+y+z=78
  (1.8y-40)+y+0.8y=78
  3.6y=78+40
  y=(118/3.6)
  y=32.78kg
  
• 10 years agoHelpfull: Yes(1) No(0)