The total cost of 2 pencils, 5 erasers and 7 sharpeners is Rs.30, while 3 pencils and 5 sharpeners cost Rs.15 more than 6 erasers. By what amount (in Rs.) does the cost of 39 erasers and 1 sharpener
exceed the cost of 6 pencils?
(1) 20 (2) 30 (3) It does not exceed (4) Cannot be determined

• Ans (2) 30
  Let the cost of a Pencil=x, Eraser=y & Sharpener=z
  Given 2x+5y+7y=30 and 3x+5z=15+6y
  For satisfying both the conditions x=2,y=1,z=3
  Therefore Cost of 39 erasers & 1 sharpener=39y+z=39(1)+3=42
  And cost of 6 pencil=6x=6(2)=12, Difference=42-12=30 Rs
• 11 years agoHelpfull: Yes(20) No(4)
• p=pencil,e=eraser,s=sharpener,x=the exceeded of 6pencils.Forming equations-
  2p+5e+7s=30.(x3)=> 6p+15e+21s=90.---(1)
  3p+5s-15=6e.(x2)=> 6p-12e+10s=30.---(2)
  39e+s=6p+x. => -6p+39e+s=x. ---(3)
  (1) + (3) => 54e+22s=90+x. ---(4)
  (2) + (3) => 27e+11s=30+x. (x2) => 54e+22s=60+2x. ---(5)
  By (4) & (5) => 90+x=60+2x.=>x= 30.
• 11 years agoHelpfull: Yes(14) No(0)
• Pl. read the equation as 2x+5y+7z=30 in the above solution instead of 2x+5y+7y=30
• 11 years agoHelpfull: Yes(2) No(2)
• let pencil =p =2; eraser = e= 1 and sharpener = s = 3;
  see 1st equ 2p+5e+7s =30;
  2*2+5*1+7*3=30 satisfied.
  now check 2nd one
  3p+5s=15+6e
  3*2+5*3=15+6*1 satisfied
  now come to the question
  39e+1s=6P+x
  39*1+1*3=6*2+x
  x=20.
  is the right answer.
• 7 years agoHelpfull: Yes(1) No(4)
• @devendra but it is very lenghty w/o calc. do u have any other way?
• 11 years agoHelpfull: Yes(0) No(2)
• 30
  Put p = 2 E = 1 and s = 3
  6p = 12
  39E + S = 42
• 7 years agoHelpfull: Yes(0) No(0)