Question

5 pencils and 7 pens together cost Rs . 50 where as 7 pencils and 5 pens together cost Rs . 46. Find the cost of one pencil and that of one pen .

Answer 1

Let the cost one pencil be Rs = x

Let the cost of one pen be Rs . y

From problem

5x + 7y = 50

7x + 5y = 46

x y (x, y) x y (x,y)

3 5 (3,5) 8 -2 (8 -2)

10 0 (10 , 0) 3 5 (3, 5)

The lines intersecting at point (3,5)

$\therefore$ Cost of one penci = Rs 3

$\therefore$Cost of one pen = 5