A single discount equivement to two successive discount of 20% and 10% on the marked price of an article is

18% 28% 24% 22%

28%

If x is first and y is second discount then, Successive discount = X + y - \(\frac{x × y}{100}\)                                 = 20 + 10 - \(\frac{20 × 10}{100}\) = 28%