The area means to multiply the length by the width.
let's solve.
14 1/2 x 13 1/4.
convert our fractions into decimals.
14 1/2 = 14.50
13 1/4 = 13.25
Now we can multiply properly.
14.50 x 13.25 = 192.125
since our shape is 2-Dimensional, our units are ^2.
Your area is:
192.25 ft^2

Hope you could get an idea from here.
Doubt clarification- use comment section.
144 - 12g^2.
Because we don't know the value of g, there's nothing else we can do.
Thanks for the helpful answers