Hello can anyone help me with these problems please and ty

12. x= 4

13. x= 4

14. x= -1

Check the steps in the picture above

(3x-8) or (3x+8)

step-by-step explanation:

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.