It is shown as a right triangle, so we can use the Pythagorean theorem:
[tex] a^{2} + b^{2} = c^{2} [/tex]
[tex] 15^{2} + x^{2} = 25^{2} [/tex]
[tex]225 + x^{2} = 625[/tex]
[tex]x^{2} = 400[/tex]
[tex]x = 20[/tex]
We can use the Pythagorean theorem to verify:
[tex]15^{2} + 20^{2} = 25^{2}[/tex]
[tex]225 + 400 = 625[/tex]
[tex]625 = 625[/tex]
This means X = 20
