Given data:
The given lenght of ZX is ZX=6x-4.
The given length of WY=4x+14
In rectangle the length of diagonals are equal.
ZX=WY
Substitute the given values in the above expression.
6x-4=4x+14
2x=18
x=9
Substitute 9 in the ZX length.
ZX=6(9)-4
=54-4
=50
Thus, the ZX lenght is 50 so the correct option is (C)