1 . Three maths classes: X, Y, and Z take an algebra test. The average score of class X is 83. The average score of class Y is 76. The average score of class Z is 85. The average score of class X and Y is 79 and the average score of class Y and Z is 81. What is the average score of the combined classes X, Y, and Z?

• A. 81
• B. 81.5
• C. 82
• D. 84.5
• D. None of these

Answer: Option B

Explanation: