Find the value of X, show work

Answer: 0
Step-by-step explanation: you just have to divide a little bit then you just multiply.
Answer: x=7.2
Step-by-step explanation:
Use the Pythagorean theorem:a^2+b^2=c^2 c being the hypothenuse and b and a being the other 2 sides
so 7.8*7.8=60.84 3*3+9 60.84-9=51.84 then the square of that would be 7.2 so x=7.2