Vertical angles are congruent.
So, we know that the line with the 60, 70, and y is supplementary since it is on a straight line. (this is given information)
So, 60+70+y= 180
130+y=180
Subtract 130 on both sides.
y=50
Vertical angles have the same measure, so <X= 50 degrees.
I hope this helps!
~kaiker