One works alone for t days and leaves, the other finishes: time for the rest

The same question, asked 4 times: 17 Jul 2023 S3*, 17 Jul 2023 S4*, 18 Jul 2023 S1*, 27 Jul 2023 S3. Every wording below, oldest first.

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Question 1
17 Jul 2023 S3
55 $Pratima and Diksha can complete a typing work separately in 10 hours and 15 hours, respectively. After typing for 4 hours alone, Pratima leaves the work. In how many hours will Diksha complete the remaining typing work?$
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Question 2
17 Jul 2023 S4
73 $A can complete a work in 18 days, while B can complete it in 12 days. B worked on it for 4 days. How long will A take to finish the remaining work?$
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Question 3
18 Jul 2023 S1
62 $A can finish a work in 20 days and B can complete the same work in 15 days. B worked for 9 days and left the job. In how many days can A alone finish the remaining work?$
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Question 4
27 Jul 2023 S3
59 $Sara can finish a work in 18 days and Tara can complete the same work in 15 days. Tara worked for 10 days and left the job. In how many days can Sara finish the remaining work alone?$
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Question 1