If 25 men earn Rs 1000 in 10 days, how much will 15 men earn in 15 days?
∵ 25 men in 10 days can earn = Rs.1000
∴ 25 men can earn in 1 day = 
∴ 1 man can earn in 1 day = 
∵ 1 man can earn in 15 days = 15 × 4 = Rs.60
∴ 15 man can earn in 15 days = 60 × 15 = Rs.900
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