A vegetable seller was selling spinach at ₹ 60 per kg. Sonu bought 350 grams of spinach for which the vegetable seller charged ₹ 21 (₹ 6 + ₹ 6 + ₹ 6 + ₹ 3) from Sonu. Which of the following is true about this mathematical skill used by the vegetable seller? Is/are the statements true?

A. This mathematical skill is vague.

B. This skill is not beneficial for solving mathematical problems in class.

C. Such skills are helpful in developing alternative ways of solving mathematical problems.