In a factory, a group of 24 workers working 7 hours a day can produce 4000 units in 30 days. In how many days will 30 workers produce 3500 units by working 8 hours a day?

Explanation: In a factory, a group of 24 workers working 7 hours a day can produce 4000 units in 30 days. In how many days will 30 workers produce 3500 units by working 8 hours a day?21