Explanation:

- A completes the work in 10 days, so A's one day's work is 1/10.

- B completes the work in 15 days, so B's one day's work is 1/15.

- Together, A and B's one day's work is 1/10 + 1/15 = 1/6.

- A's share of the work = (1/10) / (1/6) = 3/6 = 1/2 of the total work.

- B's share of the work = (1/15) / (1/6) = 2/6 = 1/3 of the total work.

- The ratio of their work = 1/2 : 1/3 = 3:2.

- Total payment is Rs. 1,250; B’s share is (2/5) of Rs. 1,250 = Rs. 500.

Option: 2, Rs. 500

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