If 7/w + 7/x = 7/y and wx = y, then the average (arithmetic mean) of w and x is Choose the correct choice from the following options.
A) 1 / 2 B) 1 C) 2 D) 4 E) 8

Rationale: given : 7 / w + 7 / x = 7 / ywx = y find : ( w + x ) / 2 = ? 7 ( 1 / w + 1 / x ) = 7 ( 1 / y ) - divide both sides by 7 ( 1 / w + 1 / x ) = 1 / y ( x + w ) / wx = 1 / wx - sub ' d in y = wx x + w - 1 = 0 x + w = 1 therefore ( w + x ) / 2 = 1 / 2 ans : a
Answer: A