The prices of tea and coffee per kg were the same in june. In july the price of coffee shot up by 20% and that of tea dropped by 20%. if in july , a mixture containing equal quantities of tea and coffee costs 90/kg. how much did a kg of coffee cost in june ?
Pick
A) 50  B) 60  C) 80  D) 90  E) 120

Rationale: "let the price of tea and coffee be x per kg in june . price of tea in july = 1.2 x price of coffee in july = 0.8 x . in july the price of 1 / 2 kg ( 900 gm ) of tea and 1 / 2 kg ( 900 gm ) of coffee ( equal quantities ) = 90 1.2 x ( 1 / 2 ) + 0.8 x ( 1 / 2 ) = 90 = > x = 90 thus proved . . . option d ."
Answer: D