we are given that
ABCD is a parallelogram
so,
AB=CD
AD=BC
Calculation of x:
AB=CD
[tex] x+30=2x-10 [/tex]
now, we can solve for x
[tex] x=40 [/tex]
Calculation of y:
AD=BC
[tex] 2y-10=y+10 [/tex]
now, we can solve for y
[tex] y=20 [/tex]
calculation of z:
[tex] z=x-y [/tex]
we got
[tex] x=40 [/tex]
[tex] y=20 [/tex]
we can plug it
[tex] z=40-20 [/tex]
[tex] z=20 [/tex]
option-B..............Answer