I don't understand this and the procedure and I can't do it, can someone tell me how it's done and how it's done?

x = 3 ± √(5+y)

first, you divide the triangle in two, tô form a retangle triangle. after, using pythagoream theorem:

18^2 = 14^2 + (x/2)^2

(x^2/4) + 196 = 324

x^2/4 = 324 - 196

x^2/4 = 128

x^2 = 512

x = √512

x = √2^9

x = 16√2 cm

i hope i you.

i'm assuming that it's c.)   volcanoes built the mountains and earthquakes tore them down.