Answer:
GH = 17
Explanation:
Given that H is the midpoint of segment GI, and GH = 5x + 2, HI = 9x - 10, GH is congruent to HI. This implies GH = HI.
Therefore:
 , which will give us the following equation:
, which will give us the following equation:

Solve for x
 (subtracting 9x from each side)
 (subtracting 9x from each side)

 (subtracting 2 from each side)
 (subtracting 2 from each side)

 (dividing both sides by -4)
 (dividing both sides by -4)

GH = 5x + 2
Plug in the value of x
GH = 5(3) + 2 = 15 + 2
GH = 17