Goods pass through a chain of sellers at successive profit or loss percents

This type of question, asked 2 times: 15 Nov 2020 Tier II, 3 Mar 2023 Tier II. All 2 questions below, oldest first.

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Question 1
15 Nov 2020 Tier II
20 $A sold a watch to B at a profit of 20%. B sold it to C at 30% profit. C sold it to D at 10% loss. If B's profit is ₹80 more than that of A, then D bought it for:$
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Question 2
3 Mar 2023 Tier II
22 $Products pass successively through the hands of three traders and each of them sells his goods at a profit of 30% of his cost price. If the last trader sold the products for Rs.300, then how much did the first trader pay for them?$
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Question 1