Answer:
D
Step-by-step explanation: always remember that sign as irrational
 
        
             
        
        
        
The inclusion/exclusion principle states that

That is, the union has as many members as the sum of the number of members of the individual sets, minus the number of elements contained in both sets (to avoid double-counting).
Therefore, 

 will have the most elements when the sets 

 and 

 are disjoint, i.e. 

, which would mean the most we can can in this case would be

(Note that 

 denotes the cardinality of the set 

.)
 
        
        
        
1- the answer is b and d 2- the answer is a and b 3- the answer is b
        
                    
             
        
        
        
Answer:
There are 60 monkeys in the Zoo
Step-by-step explanation:
In this question, we are asked to calculate the number of monkeys in a Zoo given some information to use. 
Let’s have the total number of monkeys be m. 
60% are going monkeys. This means number of young monkeys is 0.6m. 
The number of baby and old monkeys is obviously 0.4m. 
Ratio of baby to old monkeys is 3:1. This means if we splitter 0.4m into 4, number of baby monkeys is 0.3m while number of old monkeys is 0.1m 
Now, subtracting the number of baby monkeys from young monkeys give a total of 18 monkeys.
Let’s project this mathematically; 
This means ;
0.6m - 0.3m = 18
0.3m = 18
m = 18/0.3
m = 60 
There are 60 monkeys in the zoo