Answer:
Part 1) 
Part 2) 
Part 3) 
Step-by-step explanation:
see the attached figure to better understand the problem
step 1
Find the value of x
we know that
---> by addition segment postulate
we have

substitute

solve for x




step 2
Find the value of EF

substitute the value of x

step 3
Find the value of FG

substitute the value of x

To find the output when you know the input, just plug the input into the function.
x+21=4+21=25
The output is 25.
Hope this helps!
1) 7
2) irrational number (I believe)
3) square root of 441
Answer:
Quadrilaterals
Step-by-step explanation: