Question

The cost of a pen and a notebook is rs.80 . The cost of a pen is rs.10 less than that of a notebook. Find the cost of each.

Answer 1

The cost of a pen and notebook=80
so 
   take,notebook=x
           pen=(x-10)
so...x+(x-10)=80
       x+x-10=80
        2x=90
        x=45
so cost of notebook=45
    cost of pen=35

Answer 2

let notebook be=x
and,pen price be=x-10
a.p.p
x+x-10=80
2x=90
x=45
so,notebook is 45
& pen is x-10
            =45-10
            =35