Can somebody me out? this is due very soon and i am struggling

Alex drew a circle with right triangle prq inscribed in it, as shown below: the figure shows a circle with points p, q, and r on it forming an inscribed triangle. side pq is a chord through the center and angle r is a right angle. arc qr measures 80 degrees.

Determine the common ratio and find the next three terms of the geometric sequence. 10, 2, 0.4, a. 0.2; -0.4, -2, -10 c. 0.02; 0.08, 0.016, 0.0032 b. 0.02; -0.4, -2, -10 d. 0.2; 0.08, 0.016, 0.0032 select the best answer from the choices provided a b c d

What is the the greatest common factor ?