Solve for x plssss ASAP

Ill solve it using pythagorean theorem lololol
Ima show u how to tell if its a right triangle or nah
Legs 80 and 60
For this we use A^2+B^2=C^2
80^2+60^2=C^2
Lets slove it..
[tex]\left[\begin{array}{ccc}80^2+60^2=C^2\\\\80^2=6,400\\60^2=3600\\\\Add\;Them...\\\\6,400+3,600=10,000\\\\\sqrt{10,000} =100\end{array}\right][/tex]
Nope not a right triangle hence it dosent equal 51 lololllolol