cost of 7 pens and 8 pencils is Rs 87,cost of 6 pens and 4 pencils is Rs 66.find the cost of 1 pen and1 pencil frpm the graph.

Let the cost of 1 pen=Rs.x
Cost of 1 pencil=Rs.y
From the given data
7x+8y=87-------(i)
and 
6x+4y=66
$\Rightarrow$3x+2y=33----(ii)
By solving (i) and (ii) we get
x=9
y=3
Graph:

From the graph also
Cost of 1 pen=Rs.9
Cost of 1 pencil=Rs.3