Answer:
Part 1) 
Part 2) 
Part 3) 
The answer is the option A
Step-by-step explanation:
Part 1) Find the measure of side HI
Applying the Pythagoras Theorem

substitute the values and solve for HI




Part 2) Find the measure of angle G
In the right triangle GHI

substitute the values


Part 3) Find the measure of angle I
Remember that
The sum of the interior angles of a triangle must be equal to 180 degrees
so

substitute the values


Abs are not getting mad annoying you
You can try them out and see which one works.
a: f(2) = f(1) +6 = 5+6 = 11 . . . . . . not this one
b: f(1) = f(2) -6 = -1-6 = -7 . . . . . . not this one (5 ≠ -7)
c: f(2) = f(1) - 6 = 5 - 6 = -1 . . . . . this gives the right f(2)
d: f(2 = -6(f(1) = -6(5) = -30 . . . . not this one
_____
The appropriate choice is ...
... f(n +1) = f(n) - 6
— — — — —
You can also recognize that the next term is 6 less than the current one, so f(n+1) = f(n) - 6, which corresponds to the 3rd selection.
So you have to put 25 inside the blank box.
look at the attached picture
Hope it will help you
Good luck on your assignment