At noon, the temperature at a mountaintop research center is 11 degrees. Overnight the temperature drops to -19 degrees. Which expression represents how much the temperature changed?

ΔT = ( -19°C - 11°C) = -30°C

Step-by-step explanation:

When we have a given variable, let's call it X, the change of X in a given interval is written as:

ΔX = (X₂ - X₁)

Where:

X₂ = final value of the variable

X₁ = initial value of the variable.

In this case, we have the temperature, and we know that the initial temperature is 11°C, then:

T₁ =  11°C

While the final temperature is -19°C, then:

T₂ = -19°C

Then the change will be:

ΔT = ( -19°C - 11°C) = -30°C

This is the wanted expression.

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