Answer: The ratio 16:12 describes the ratio of the number of students who play the viola to the students who play the clarinet.
Step-by-step explanation:
Given : Number of students who play the clarinet= 12
Number of students who play the viola=16
We know that ratio of A to B is represented by A:B.
Since, the number '12' is representing " students who play the clarinet" and number '16' is representing " students who play the viola"
So , the ratio 16:12 describes the ratio of the number of students who play the viola to the students who play the clarinet.
39/1.5 = 26 km per hour
51/3 = 17 km per hour
Then you need the mean. 26+17/2 = 21.5 km per hour
notice that the denominator can be factored into (x-3)(x+3).
Now you can cross out (x - 3) from the numerator and denomiantor resulting in a simplified fraction of 
Plug the limit value (which is 3) into the simplified fraction.
Answer: 

By inspection 1 is a root of y ,
Hence , (x-1) is a factor of y ,

Hence , the 2 other roots are -1/2 and 3 , and the above graphs confirms the same.
Hope it helps you :)