Q: If $$ \ {xy\over x+y}= a, $$ $${xz\over x+z}=b $$ and $$ {yz\over y+z} =c $$ where a, b, c are all non – zero numbers, then x equals to

• A. $$ 2abc\over {ab+bc-ac} $$
• B. $$ 2abc\over {ab+ac-ac} $$
• C. $$ 2abc\over {ac+bc-ab} $$
• D. $$ 2abc\over {ac+bc-ac} $$