You need to cut a 9 foot piece of plywood into 12 inch sections. every cut also removes 1/8 inch. how much of the plywood will be left after cutting the 12 inch sections?

There are 9 feet so it would usually be nine 12" pieces but since each cut takes away 1/8, you can only cut 8 pieces equal to 12 inches. 

Considering this fact, each cut would take away 0.125 inches. If you're cutting 8 times, you would in all be taking away 1 inch.

So aside from the eight 12" sections, you would have a leftover of 11 inches.

It will take him 5 days