Answer:
To find the sum of interior angles in a polygon, we can use the formula:
where n is the number of sides.
Since this is pentagon (5 sides), then 
The missing angle would then be

Since angles on a straight line add up to 180, then


10-6v+9v=28
10+3v=28
-10 -10
3v=18
3 3
v=6
If the triangle is a right triangle, the pythagorean theorem would work
since it doesn’t, the triangle is NOT A RIGHT TRIANGLE
(see attached pic for work :))
I believe it’s D. Y=5
If it’s not right , I apologize
Good luck
If it takes eight men ten hours, it would take seven men nine hours, six men eight hours, five men seven hours and that brings us to the answer you need. It would take four men six hours.