Please I need help it’s an emergency

Answer:
A. [tex] 4\sqrt{6} [/tex]
Step-by-step explanation:
Applying the leg rule which is:
[tex] \frac{Hypotenuse}{leg} = \frac{leg}{part} [/tex]
Hypotenuse = 4 + 8 = 12
Leg = x
Part = 8
Plug in the values
[tex] \frac{12}{x} = \frac{x}{8} [/tex]
Cross multiply
[tex] x*x = 8*12 [/tex]
[tex] x^2 = 96 [/tex]
[tex] \sqrt{x^2} = \sqrt{96} [/tex]
[tex] x = \sqrt{16 * 6} [/tex]
[tex] x = 4\sqrt{6} [/tex]