Help on 4 plz quick also if you can

The area of the rect. is 100 ft times 64 ft, or 6400 ft^2.
Let's list factors of 6400: 64,100
64= 2^6
100= 2^2*5^2
Here we see that 2 appears 8 times as a factor, and 5 appears 2 times:
6400 = 2^6 * 10^2 = 2^8*5^2