Dear Armen.

 Please consult

https://sites.math.rutgers.edu/~zeilberg/Hist21/mt1S.pdf

for the full solutions.

You got  93 points (out of 120).

Here is what you got wrong:

#4: -10 points (not attempted)

#5: -5 points, you did not explain, and the square you got is not what you get using the method (did you just google it?)

#7: -2 points (EF is a s um of DISTINCT unit fractions)

#12: -10 points (right answer but the way requested, you used the definition, and I suspect that you used Maple, at any rate you did not explain)






 Best wishes,

   Dr. Z.