Answer:
B
Step-by-step explanation:
The angle measures tell you the triangles are similar, so corresponding sides will have the same ratio.
GX/BX = UH/NH
GX = BX·UH/NH
GX = 7·18/(3√11)
GX = (42/11)√11
GB/BX = UN/NH
GB = BX·UN/NH
GB = 7·15/(3√11)
GB = (35/11)√11
The x^2 over the x is like subtracting x from x^2, so the new equation would be 9-x/-3. You divide 9 by -3 to get the final answer of -3-x, or -x-3, which is E.