1/a+b+c=abc/1000
<=>abc.(a+b+c)=1.1000=1000
Nhận thấy abc là ước có 3 chữ số của 1000
=>abc E {100;125;200;250;500}
+)abc=100=>a+b+c=10( loại)
+)abc=125=>a+b+c=8( nhận)
+)abc=200=>a+b+c=5( loại)
+)abc=250=>a+b+c=4( loại)
+)abc=500=>a+b+c=2( loại)
Vậy abc=125 và a=1;b=2;c=5
Theo bài ra ta có : 1 : abc/1000 = a+b+c
1000 : abc = a+b+c
Do 1000 chia hết cho abc và abc là số có 3 chữ số nên có thể = 500 ; 250 ; 200 ; 125.
Thay từng giá trị vào đề bài, ta tìm được abc = 125
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