The total cost of 12 pens and 5 pencils is equal to ₹ 111. Also, the cost of 1 pencil is ₹ 5 less than the cost of 1 pen. What will be the cost of 8 pens and 9 pencils?

Let the cost of 1 pencil = x
∴ Cost of 1 pen = (x + 5)
According to the question,
12(x + 5) + 5x = 111
⇒ 12x + 60 + 5x = 111
⇒ 17x = 111 - 60 = 51
⇒ x = 51/17 = 3
∴ Cost of 1 pencil = ₹ 3
Cost of 1 pen = ₹ 8
∴ Total Cost of 8 pens and 9 pencils
= (8 x 8 + 9 x 3)
= ₹(64 + 27) = ₹ 91