Help, please, what is the answer??

Answer:
18.0
Step-by-step explanation:
The three lines form a right triangle where 10 and 15 are the two legs of the triangle. You can use the pythagorean theorem to solve for the length of x.
x = [tex]\sqrt{15^{2} + 10^{2} }[/tex]
x = 18.028 (approximately 18)