30 men can plant 100 trees in 9 days, 

If we divide the number of men by 5 we must multiply the
number of days by 5, so

6 men can plant 100 trees in 45 days,

For 6 men to plant 4400 trees, it will take 44 times as long, so

6 men can plant 4400 trees in 1980 days,

If we multiply the number of men by 6 to get 36 men, we must divide
the number of days by 6. So

36 men can plant 4400 trees in 330 days,

Edwin