Question

Kapil paid Rs.30 for pen and book. If the cost of the book is double the cost of the pen then Find the cost of 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