Could someone me with both of these questions?

What are the coordinates of the midpoint of ab? ,1/2) /2,-1) ,-3/2) /2,-2)

Me n o w. i need t h i s. 10 points

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.