The cost of 21 pencil and 9 clippers is ₹ 819. What is the total cost of 7 pencils and 3 clippers together?

Let cost of 1 pencil and 1 clipper be p and c, respectively.
Now, according to the question,
21p + 9c = ₹ 819
⇒ 3(7p + 3c) = ₹ 819
₹ 7p + 3c = ₹ 273
Cost of 7 pencil and 3 clippers = ₹ 273