Find the mean age of the swimmers on the team.

 10

Work Shown:

First add up all the ages

9+13+9+10+10+9+10+10+11+9 = 100

Then divide that sum by 10, since there are 10 values we added up

100/10 = 10

The average age is 10 years old.

100÷25x20+4÷2-14
Remember to follow the order of operations, Parenthesis Exponents Multiplictation Division Addition Subtraction (PEMDAS)
                                                                
following tat, we would do the division first                    
4x20+4÷2-14
(100/25=4)

80+4÷2-14
(20x4=80)

Now we do 4÷2 (remember, you do multiplication and division first)
80+2-14

now we just add and subtract from left to right:
(80+2=82)
82-14

68 is your final answer