Since there are 100 units, the number of units occupied by tenants is 3/4 * 100 = <<3/4*100=75>>75
If each tenant pays $400 every month, Mr Maximilian receives 75 * $400 = $<<75*400=30000>>30000 in rent revenue every month.
In a year, Mr Maximilian receives $30000 * 12 = $<<30000*12=360000>>360000 in rent revenue.
#### 360000