Everyone should pay $10.2\times5=51$ dollars. $51\times 6=306$ 
Six friends went to hike together and agreed to share the bill equally. However, James forgot to bring his wallet, so each of his five friends paid an extra of $10.2$ dollars to cover James\textquotesingle~portion. How much did they have to pay in total? 

a. $$51$$ 
b. $$58.4$$ 
c. $$255$$ 
d. $$306$$ 
e. $$308.8$$ 