Answer
624 $ft^{2}$
Work Step by Step
Lets divide the given diagram into two rectangles
Dimensions of the rectangle 1 be b= 30ft and h= 18ft
As we know the area of the rectangle with the length of the base b and length of the altitude h is A = bh
A = 30 * 18 = 540 $ft^{2}$
Now dimensions for the 2 rectangle be b = 14ft and h = 24 -18 = 6ft
As we know the area of the rectangle with the length of the base b and length of the altitude h is A = bh
A = 14 * 6 = 84$ft^{2}$
Total area of the room = area of 1 rectangle + area of the 2 rectangle
= 540 + 84
= 624 $ft^{2}$