The GCF is 8, you can also double check my work by dividing 24/8, then 40/8
The surface area of it is 164 because you multiply each side by the length of the height and width and then add them all together
So he worked 30.5 hours, he just didn't write some of the hours down. To find the hours he didn't write down, you subtract 8+

+

from 30.5, which equals
First one is $16 and the second is $276.25