The angle x is correspondant angle of the one marked with 110, so it is an angle of 110 as well.
The angle immediately above y measures 110 as well, and together they form an angle of 180, so you have
[tex] 110+y=180 \implies y= 70 [/tex]
Finally, the sides labeled with 3, 6, 4 and c are in proportion, so you have
[tex] 3:6 = 4:c [/tex]
And so you have
[tex] c = \dfrac{6\cdot4}{3} = 8 [/tex]
