Explanation:

- To find a single discount equivalent to two successive discounts, use the formula:

$$

\text{Single Discount} = a + b - \frac{ab}{100}

$$

where \( a \) and \( b \) are the successive discounts.

- Calculate for 12% and 8%:

$$

\text{Single Discount} = 12 + 8 - \frac{12 \times 8}{100}

= 20 - 0.96

= 19.04\%

$$

- Option 1: 19%

- This option rounds 19.04% to 19%.

- Correct answer:

- Option 2: 20%

- Incorrect, overestimates the discount.

- Option 3: 18%

- Incorrect, underestimates the discount.

- Option 4: 17%

- Incorrect, significantly underestimates the discount.