Answers

2014-11-23T15:45:55+05:30
The cost of notebook = "x"
The cost of the pen = "2y"
(y x 2 because it is twice of the notebook)

=> x - 2y=0

hope helped you
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2014-11-23T15:49:01+05:30
Take pen has X and notebook has y
x=twice
y=1y
so 2x-y=0
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