3 is the greatest common denominator
No.
Double 5 and add 1 is 5(2)+1 = 11
Add 1 to 5 then double it: (1+5)2 = 12
In Cartesian coordinates, the region is given by

,

, and

. Converting to cylindrical coordinates, using

we get a Jacobian determinant of

, and the region is given in cylindrical coordinates by

,

, and

.
The volume is then
Rule: The diagonals of any parallelogram bisect each other. In other words, they cut each other in half.
This means DF is cut into two equal pieces: DH and HF.
Similarly, GE is cut into two equal pieces: GH and HE.
DH = HF
x+5 = 2y
x = 2y-5
GH = HE
4x-3 = 4y+1
4(x)-3 = 4y+1
4(2y-5)-3 = 4y+1 ... x has been replaced with 2y-5
8y-20-3 = 4y+1
8y-23 = 4y+1
8y-4y = 1+23
4y = 24
y = 6
If y = 6, then x is
x = 2y-5
x = 2(6)-5
x = 12-5
x = 7
--------------------------------------------
Answers:
x = 7 and y = 6