An exam is given in a certain class. The average (arithmetic mean) of the highest score and the lowest score is equal to x. If the average score for the entire class is equal to y and there are z students in the class, where z > 5, then in terms of x, y, and z, what is the average score for the class excluding the highest and lowest scorers?  Choose the correct choice from the following answers
A) (zy – 2x)/z  B) (zy – 2)/z  C) (zx – y)/(z – 2)  D) (zy – 2x)/(z -2)  E) (zy – x)/(z + 2)
Highest: H   Lowest: L   Number of students in the class: Z   Number of students in the class excluding the highest and lowest : Z-2   Average of Highest and Lowest: (H + L)/2=X =&gt; H+L=2X   Average of Entire Class : (H+L+Others)/Z=Y =&gt; Others= ZY-2X   Average of the others in the class: (ZY-2X)/(Z-2)   Answer: (zy – 2x)/(z -2)
<result>D</result>
An exam is given in a certain class. The average (arithmetic mean) of the highest score and the lowest score is equal to x. If the average score for the entire class is equal to y and there are z students in the class, where z > 5, then in terms of x, y, and z, what is the average score for the class excluding the highest and lowest scorers?