Amy has 1/2 hour to do 3 chores. she plans to spend the same fraction of an hour on each chore. she wants to use the number line to her determine what fraction of an hour she can spend on each chore. what is the correct number label for point a?

Point A would be zero; Point B, the end of the 1/2-hour time interval, would be 1/2 (representing 1/2 hour).  Then Amy needs to subdivide the interval A to B into three equal time intervals and to determine the length of each of these subintervals.

I would begin with 1/2 and divide that by 3:  

1
--
2

   3
   --
    1

Inverting the fraction in the denom. and multiplying, we get

1      1       1
-- * =
2      3        6

So Amy will spend 1/6 th of an hour, or 10 minutes, on each chore.

Note that 3 times 1/6 comes out to 1/2 (hour), which is were we started.