Option (D) is the correct answer.
Given:
The objective is to find the expression for the average of x, 2x, and 3y.
The average of a terms is the ratio of sum of all the terms to the total number of terms.
Then, average for the given terms can be calculated as,
[tex]\begin{gathered} \text{Average}=\frac{x+2x+3y}{3} \\ =\frac{3x+3x}{3} \\ =\frac{3(x+y)}{3} \\ =x+y \end{gathered}[/tex]Hence, option (D) is the correct answer.
