Somebody please help!

What's the difference between: x≥0 and nonnegative integer. ?

Which of the following statements is not true? a.parallel lines are lines in the same plane that never intersect. b.congruent figures have the same shape and same size angles and sides. c.similar figures must have the same shape and the same size. d.a rotation is when you turn a figure around a certain point.

1.based of the diagrams what is the the value of x? 2.how would you verify your answer for x