### Video Transcript

Evaluate 𝑥 plus 𝑦 plus 𝑧 plus six for 𝑥 equals negative five, 𝑦 equals negative six, and 𝑧 equals negative nine.

We are told in the question that 𝑥 equals negative five, 𝑦 is equal to negative six, and, finally, 𝑧 is equal to negative nine. To evaluate 𝑥 plus 𝑦 plus 𝑧 plus six, we need to add negative five, negative six, negative nine, and positive six. Adding a negative number is the same as subtracting that number.

This leaves us with negative five minus six minus nine plus six. Negative five minus six gives us negative 11. Subtracting nine from this gives us negative 20. Negative 20 plus six is equal to negative 14. The value of 𝑥 plus 𝑦 plus 𝑧 plus six when 𝑥 equals negative five, 𝑦 equals negative six, and 𝑧 equals negative nine is negative 14.