stapel

What is "the equation"? Why do you think that "x = -1" is one of the number you are required to use? (Why aren't you allowed to just pick whatever x-values you like, as is the norm?)

The sixty houses take (10 men)(120 days) = 1200 man-days to complete. Then one house would take (1200 man-days) / (60 houses) = 20 man-days / house. How many man-days are required for thirty houses? If those man-days are divided amongst five people, how m...

I don't know what you might mean by "something else", but a function should be defined in your book. In short, if any x-value leads to two or more y-values, then whatever relation you have is not a function. I can't see your graphs or columns or whatever,...