一袋代幣有11個,共重78g。其中10個普通版代幣的重量相同,餘下1個特別版代幣的重量是普通版的2倍。一個普通版代幣的重量是多少?
A bag of coins weighs 78g. There are 11 coins in the bag. 10 of them are of the standard edition and each of them weighs the same. The remaining one is of the special edition and weighs 2 times as heavy as the standard edition. What is the weight of the coin of the standard edition?
A. 6g
B. 6.5g
C. 7.09g
D. 7.8g