abc=xyz-zyx=(100x+10y+z)-(100z+10y+x)=99(x-z)=99n,
where n=x-z can be any of 1,2,3,..,9 since x>z
but abc=99n can be expressed as:
abc=99n=100*(n-1)+ 10*9+ (10-n),
so a=n-1, b=9, c=10-n
Therefore, abc+cba=1089
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abc=xyz-zyx=(100x+10y+z)-(100z+10y+x)=99(x-z)=99n,
where n=x-z can be any of 1,2,3,..,9 since x>z
but abc=99n can be expressed as:
abc=99n=100*(n-1)+ 10*9+ (10-n),
so a=n-1, b=9, c=10-n
Therefore, abc+cba=1089
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