Answer:
648
Step-by-step explanation:
Number of Assaults, n(A)=430
Number of Robberies, n(R)=146
Number of Drug Sales Offenses, n(D)=131
Number involved in both assault and robbery= 
Number involved in both assault and drug sales= 
Therefore, to find the greatest possible number of offenders for May who satisfy these statistics, we remove the number of those who were involved in more than one crime.
This gives us:

The greatest possible numbers of offenders in May is 648.