Can someone help explain this to me ?​

L2.8.2 test (cst): triangles in the figure, pq is parallel to rs. the length of rp is 5 cm; the length of pt is 30 cm; the length of q7 is 60 cm. what is the length of so? o a. 20 cm 0 0 o b. 6 cm o c. 10 cm od. 2 cm 0 previous