In what ratio mental A at Rs.68 per kg be mixed with another metal at Rs.96 per kg so that cost of alloy (mixture) is Rs.82 per kg?  Choose the correct choice:
A) 5 : 8
B) 4 : 7
C) 3 : 7
D) 1 : 1
E) 9 : 8

Rationale: "( 96 - 82 ) / ( 82 - 68 ) = 14 / 14 = 1 / 1 answer : d"
Answer: D