If the single discount equivalent to successive discounts of 20% and x% is 24%, then the value of x is:

Let the marked price = M

Price after 20% discount = $$\frac{80}{100}\text{M}$$

Selling price after $$x$$% successive discount = $$\frac{100-x}{100}\times\frac{80}{100}\times \text{M}$$

Overall discount = 24%

Selling price after 24% discount = $$\frac{76}{100}\text{M}$$

$$=$$>  $$\frac{76}{100}\text{M}=\frac{100-x}{100}\times\frac{80}{100}\times \text{M}$$

$$=$$>  $$95=100-x$$

$$=$$>  $$x=5$$

Hence, the correct answer is Option B