1. What is shadowed surface of cube if its side is $\displaystyle a=2\sqrt{2}$

(Image is on attachment).

2.On the box, we have 5 red balls, 4 dark balls, and 6 white balls. If we catch one ball, what is probability to catch a white one?

3. If we have a segment [AB], A(5,-1), B(x,2) and it's middle point is O(0,0), what is value of x?

Thank you.