Let me explain this in 2 parts as it may be hard to understand if it's explained all at once.
x(squared)= 9(squarded) - 5(squared)
So that is 9x9=81, and 5x5=25.
81+25= 106
So then... 106= X(squared)
106(square root)
10.3=x
Part 2 is the second triangle.
y(squared)= 5(squared) + 3(squared)
So that's 5x5= 25 and 3x3= 9.
25+9= 34
So then... 34= Y(squared)
34(square root)
5.8=y
Final Answers are....
X= 10.3
Y= 5.8
Hope this helped. :)