7.39 persons can repair a road in 12 days working 5 hours a day in how many days will 30 persons working 6 hours a day complete a work

39 people : 12 days : 5 hours

//Find 1 person

1 person : 12 x 39 days : 5 hours

1 person : 468 days : 5 hours

//Find 30 people:

30 people : 468 : 30 days : 5 hours

30 people : 15.6 days : 5 hours

//Find 1 hour:

30 people : 15.6 x 5 days : 1 hour

30 people : 78 days : 1 hour

//Find 6 hours:

30 people : 78 : 6 days : 6 hours

30 people : 13 days : 6 hours

Answer: 13 days