Răspuns :
[tex]\overline{a5c9} = 3\times 1000 + b \times 100 + 7 \times 10 + d \\ \\ \overline{a5c9} = \overline{3b7d} \\ \\ \boxed{\Longrightarrow ~~ a=3,~~b=5,~~c=7,~~d=9 } \\ \\ \boxed{\Longrightarrow ~~\overline{a5c9} == \overline{3b7d}= 3579}[/tex]