Explanation:

- The shopkeeper gives two discounts, 15% followed by 20%.

- Selling price after these discounts is 68% of the marked price (0.85 * 0.80 = 0.68).

- Despite this, he earns a 70% profit.

- If the marked price is denoted by M and cost price by C, then:

$$

\frac{0.68 \times M}{C} = 1.70

$$

This implies $$M=\frac{1.70C}{0.68}$$.

- For a single 30% discount, the selling price is 70% of M.

- Substitute $$M=\frac{1.70C}{0.68}$$:

Selling price = 0.70 * $$\frac{1.70C}{0.68}$$ = 1.75C.

- The profit percentage with a 30% discount is 75%.

- Answer: Option 2 - 75%