Question

this pen cost 12 rupees ( cost is the underlined word use it as a noun)

Answer 1

Answer:

The price of this pen  is 12 rupees.

Instead of cost have used Price.

Hope it hepls!

Answer 2

Explanation:

Using cost as a Noun:

★ The Cost of this pen is 12 rupees.

or

★ Cost of this pen is 12 rupees.

Thanks!