Q.An article is marked at ₹1,000. Successive discounts of 20% and 10% are allowed on it. Find the final selling price and the single discount equivalent to these two.

The second discount is applied to the price left after the first, so the two discounts are multiplied, not added.

Here $MP=₹1{,}000$ with successive discounts of $d_1=20\%$ and $d_2=10\%$.

Step 1 — Apply the first discount. After 20% off, the price is

Step 2 — Apply the second discount on the reduced price. The 10% is taken on ₹800, not on ₹1,000:

So the final selling price is ₹720. …

Multiplying-factor method: the overall factor is $0.80\times0.90=0.72$, so the article sells for $72\%$ of its marked price. The single equivalent discount is therefore $100%-7 …

The classic error is adding the discounts to get 30% and computing $SP=1000\times0.70=₹700$. Because the 10% is charged on the already-reduced ₹ …