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To determine the BTU output for a coil based on given airflow and temperature data, you can use the formula:

\[ \text{BTU/hr} = \text{CFM} \times 1.08 \times (\text{LAT} - \text{EAT}) \]

In this formula:

- CFM stands for Cubic Feet per Minute, representing the airflow rate.

- 1.08 is a constant that accounts for the density of air and specific heat.

- LAT is the Leaving Air Temperature, and EAT is the Entering Air Temperature.

Given the values:

- CFM = 21,000

- EAT = 67°F

- LAT = 84°F

The difference in temperature is:

\[ \text{LAT} - \text{EAT} = 84°F - 67°F = 17°F \]

Now plug in the numbers into the formula:

\[ \text{BTU/hr} = 21,000 \times 1.08 \times 17 \]

First, calculate \( 1.08 \times 17 \):

\[ 1.08 \times 17 = 18.36 \]

Next, multiply by the CFM: