Slope if distance time graph represent velocity or speed.
Yes, it can be parallel to time axis if the object is at rest position
Here, Angles under a straight line would be equal to 180
So, 70 + 60 + y = 180
130 + y = 180
y = 180 - 130
y = 50
Now, x = y [ As they are vertically opposite angles ]
In short, Your Answer would be 50
Hope this helps!
