Answer:
By applying Pythagoras theorem
Answer is √[109] inch
2/3 + 3/4 = 8/12 + 9/12 = 17/12 = 1 5/12
1 + 5/12 = 12/12 + 5/12 = 17/12 = 1 5/12
2/3 + 3/4 = 1 + 5/12
Answer: (D) 
Explanation:

Just a note on writing down these expressions: I recommend using parentheses whenever you can to avoid misinterpretation. An expression 1/x-1/y / 1/x+1/y could be interpreted by someone as 1/x-(1/y / 1/x)+1/y, which is a different thing.
Answer:
Step-by-step explanation:
9000000 - 900 = 8999100