+23254 To begin with, you will need to hire at least 85 employees (to monitor water pollution).
If 27 of these can also monitor air pollution, you will need 73 - 27 = 46 persons who can monitor only air pollution.
So, you will need to hire 85 + 46 = 131 persons.
Another way is to add 85 (water) + 73 (air) to give 158 persons. But since 27 handle both, subtract 27 from 158 to give you 131 persons.
+23254 To begin with, you will need to hire at least 85 employees (to monitor water pollution).
If 27 of these can also monitor air pollution, you will need 73 - 27 = 46 persons who can monitor only air pollution.
So, you will need to hire 85 + 46 = 131 persons.
Another way is to add 85 (water) + 73 (air) to give 158 persons. But since 27 handle both, subtract 27 from 158 to give you 131 persons.
