$a)720\sout{0}:9\sout{0}=720:9=80$

$b)39\sout{000}:13\sout{000}=39:13=3$  

$c)2490\sout{00}:3\sout{00}=2490:3=830$

$d)665\sout{0000}:7\sout{0000}=665:7=95$

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