4, ?, 68 what does that mean?

Which choice represents the sample space ,s for this event

Prove that quadrilateral is a rhombus.

Three numbers x, y, and z are in the ratio 2: 7: 8. if 12 is subtracted from y, then three numbers form a geometric sequence (in the order x, y–12, z). find x, y, and z. there are 2 sets.