Driveway question

Today Mr Max showed us how to do the driveway question on excel. Its deadly. He showed up how to use the roundup forumla which rounds up the decimal to a certian decimal place. I also finshed the picnic table question. It confused me by the footage but i forgot you can't put two boards inline with each other while making the table so that change my cost. i missed yesterdays class so im trying to get caught up.