If on a marked price, the difference of selling prices with a discount of 30 % and two successive discounts of 20 % and 10 % is ₹ 72, then the marked price (in ₹) is

Let the marked price = ₹ N
The discount equivalent to successive discounts 20 % and 10 % = { r₁ + r₂ - (r₁ r₂)/100 } %
Where, r₁ = 20 and r₂ = 10
Then, 30 - 2 = 28 %
According to the question,
{(100 - 28)N}/100 - {(100 - 30)N}/100 = 72
⇒ (72N - 70N)/100 = 72
∴ N = (72 x 100)/2 = ₹ 3600