Answer
$CFM=270 \;ft^3/min.$
Work Step by Step
Area of the room
$A=24\;ft\times 14\;ft$
$A=336\;ft^2$
Air changed per hour
$ACH=6$
Height
$H=8.0\;ft$
The formula for the $CFM$ is
$CFM=\frac{ACH(A\times H)}{60}$
Substitute all the values.
$CFM=\frac{6(336\;ft^2\times 8.0\;ft)}{60\;min}$
$CFM=268.8 \;ft^3/min.$
$CFM=270 \;ft^3/min.$
