5 pencil 4 pen and 5 register costs 87 and 3 pencil 2 pen 7 register costs 91 then combined cost of i pencil i pen and 1 register ??

• x=pencil, y=pen, z=register
  5x+4y+5z=87...(i)
  3x+2y+7z=91...(ii)
  - ii from i
  2x+2y-2z=-4
  or
  x+y+2=z...(iii)
  put iii in i we get
  10x+9y=77
  or
  x=1/10(77-9y)
  using hit n trial we get
  when y=3,x=5.
  put these in i,we get
  z=10.
  ans- x=5,y=3,z=10
• 11 years agoHelpfull: Yes(15) No(0)
• Cost of 1 pencil=5,cost of 1 pen=3,cost of 1 register=10...
  so,total cost=18
  eq.1 5x+4y+5z=87;eq2: 3x+2y+7z=91...by solving these two eqs. we get...2x+2y+4=2z
  hence z=(2x+2y+4)/2 and put the value of z in any one eqn.,we get
  10x+9y=77 and apply hit n trial method
• 11 years agoHelpfull: Yes(5) No(0)