Question

Kapil paid rs 30 for a pen and a book.If the cost of the book is double the cost of the pen,then find the cost of the book.

Answer 1

let the cost of book be x and cost of pen be y

as per the question x+y=30------equation 1

it is also given that cost of book is double the cost of pen so

x=2y-------- equation 2

substituting x=2y in equation 1 we get

2y+y=30
3y=30
y=30/3=10

substituting y=10 in equation 2 we get

x=2{10}
x=20
cost of book is 20 and cost of pen is 10
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