Alloy A contains iron and copper in ration 4 : 5. Alloy B contains iron and copper in ratio 3 : 4. If 45 kg of alloy A and 63 kg of alloy B are mixed, then what is the final ratio of copper and iron?

A

61 : 47

B

64 : 47

C

57 : 41

D

59 : 45