Can I get help with these two questions?

Find the value of x for which abcd must be a parallelogram -9-6x x-30

In right ∆abc shown below, the midpoint of hypotenuse ac is located at d and segment bd is drawn.if ab = 12 and bc = 16, then explain why bd = 10. hint: consider what you know about the diagonals of a rectangle.

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?