In the figure below
1) Using the theorem of similar triangles (ΔBXY and ΔBAC),

Where

Thus,

thus, BC = 7.5
2) BX = 9, BA = 15, BY = 15, YC = y
In the above diagram,

Thus, from the theorem of similar triangles,

solving for y, we have

thus, YC = 10.
1 3/7 ~ One and three sevenths
True
The two shorter lengths do not add up to more than the longest length. 3+3 is less than 9. Therefore, even if the two shorter lengths lay on top of the longer side, the two ends cannot meet to form a closed 3 sided figure
If 4 lbs of potatoes cost 6.78...then 1 lbs of potatoes cost 6.78/4 = 1.695...rounds to 1.70 per lb
31 units
the outer part,try to combines pieces that would make one unit and count