Math question I need major help?

What is the geometric mean of 7 and 12. 2). The altitude of the hypotenuse of a right triangle divides the hypotenuse into segments of lengths 14 and 8 what is the length of the altitude? 3). In triangle DEF, the bisector of angle F divides the opposite sides into segments that are 4 and 9 in. Long. The side of the triangle adjacent to the 4 in. Segment is 6 in. Long. To the nearest tenth of an inch how long is the 3rd side of the triangle. 4). In triangle QRS, XY is parallel to SR. XY divides QR and QS into segments as follows: SX=3, XQ= 2x, RY= 4.5, and YQ = 7.5. Write a proportion to find x. What is the length of QS?