A building operations manager in Denver is analyzing temperature fluctuations to optimize heating systems. According to the course content, the records show a lunchtime temperature of $-6$ degrees and a sunset temperature of $-15$ degrees. Match each part of the temperature difference calculation to its correct numerical value or mathematical expression.

A facility manager in Denver is reviewing a daily temperature log to monitor the building's heating system performance. The log shows that at lunchtime, the temperature was $-6$ degrees, and by sunset, it dropped to $-15$ degrees. Based on the course material, what is the initial mathematical expression used to determine the difference between the lunchtime and sunset temperatures?

A facility operations manager in Denver is analyzing temperature fluctuations to ensure building efficiency. The log shows a lunchtime temperature of $-6$ degrees that dropped to $-15$ degrees by sunset. To find the difference, the manager uses the expression $-6 - (-15)$. According to the subtraction strategy, this expression is simplified by replacing the subtraction of a negative with the addition of a positive: $-6 +$ ____.

A logistics coordinator in Denver is documenting temperature changes for a climate-controlled shipment. The records show a lunchtime temperature of $-6$ degrees, which dropped to $-15$ degrees by sunset. Arrange the following steps in the correct order to calculate the temperature difference using the subtraction strategy described in the course.

A logistics coordinator in Denver is tracking temperature shifts that could affect sensitive inventory. According to the Denver scenario discussed in the course, the calculated difference between a lunchtime temperature of $-6$ degrees and a sunset temperature of $-15$ degrees is 9 degrees.