Selling price raised by a fixed amount (cost price possibly changed) moves the profit percent: find the cost or selling price

This type of question, asked 2 times: 15 Nov 2020 Tier II, 8 Aug 2022 Tier II. All 3 questions below, oldest first.

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Question 1
15 Nov 2020 Tier II
9 $Remi earns a profit of 20% on selling an article at a certain price. If she sells the articles for ₹8 more, she will gain 30%. What is the original cost price of 16 such articles?$
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Question 2
8 Aug 2022 Tier II
22 $A person sells an article for a loss of 18 percent. If he increases the selling price by ₹ 144 and decreases the cost price by 30 percent, then there is profit of 20 percent. What is the original selling price?$
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Question 3
8 Aug 2022 Tier II
18 $An article is sold at 25 percent loss. If its cost price is doubled and selling price is increased by ₹ 660, then there is a profit of 20 percent. What is the original cost price of the article?$
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Question 1