If x is the average (arithmetic mean) of m and 9, y is the average of 2m and 15, and z is the average of 3m and 18, what is the average of x, y, and z in terms of m?

A) m+6
B) m+7
C) 2m+14
D) 3m+21

B

Explanation:

Let's convert these written languages into mathematical expressions:

"x is the average of m and 9": x =

"y is the average of 2m and 15": y =

"z is the average of 3m and 18": z =

Now, we want to find the value of the average of x, y, and z in terms of m. The average of x, y, and z can be written as: . Let's substitute each of the expressions we have above in for x, y, and z:

The answer is B.

Hope this helps!