Since triangle EFG is congruent to triangle RST, you can correspond the respective legs, hypotenuse, and angles to one another as all angles and side lengths are equal to each other.
Solving for x (right angles):
(4x+6) degrees = 90 degrees
4x=84
x = 21
Solving for y (acute angles):
(5y-2) degrees = 28 degrees
5y=30
y = 6
Solving for z (hypotenuses):
z+4 = 3z-8
z = 3z-12
-2z = -12
z = 6
Solving for angle F:
180 - (acute angle) - (right angle)
180 - 28 - 90 = 62 degrees
Note that 180 degrees is the total value you get when adding all angles up in all triangles regardless of shape.
Solving for side length ST:
Use z+4 and how z = 6
6+4 = 10
ST = 10
Hope this helps!