Explanation:

- Let's break this down: When the cost price of 70 articles equals the selling price of 40, it means there is a profit.

- Consider the cost price for one article as 'C'. Thus, the cost price of 70 articles is 70C.

- The selling price of these 40 articles is equal to 70C (as given in the problem).

- Hence, the selling price of one article is \( \frac{70C}{40} = 1.75C \).

- The profit on one article is \( 1.75C - C = 0.75C \).

- Profit percentage is calculated as \( \frac{\text{Profit}}{\text{Cost Price}} \times 100\).

- Therefore, the profit percentage is \( \frac{0.75C}{C} \times 100 = 75\% \).

- The correct option is Option 1: 75%

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