$$\left( 7\frac{4}{25}+8.6 \right)\div \left[ \left( 4\frac{5}{7}-0.005\times 900 \right)\div \frac{6}{7} \right]$$  $$=\left( 7.16+8.6 \right)\div \left[ \left( 4\frac{5}{7}-4.5 \right)\div \frac{6}{7} \right]$$  $$=15.76\div \left( \frac{3}{14}\times \frac{7}{6} \right)$$  $$=15.76\div \frac{1}{4}$$  $$=15.76\times 4$$  $$=63.04$$  故答案为：$$63.04$$． 
计算：$$\left( 7\frac{4}{25}+8.6 \right)\div \left[ \left( 4\frac{5}{7}-0.005\times 900 \right)\div \frac{6}{7} \right]=$$~\uline{~~~~~~~~~~}~． 
a: $$63.04$$ 
b: $$634$$ 
c: $$620$$ 
d: $$6304$$ 