What percentage above the cost price should a seller mark his goods so that, after allowing a discount of 20% on the marked price, he can earn a profit of 4%?

25% 28% 42% 30%

30%

CP                    MP       100 - D%           100 + P%      100 - 20%           100 + 4%          80                      104 The percentage at which he marks up the CP = ( 104 - 80 ) × \(\frac{100}{80}\) = 30%