Răspuns :
a+b+c=999
a+b=656
b+c=504
656+c=999
c=999-656
c=343
b+343=504
b=504-343
b=161
a+161=656
a=656-161
a=495
a+b=656
b+c=504
656+c=999
c=999-656
c=343
b+343=504
b=504-343
b=161
a+161=656
a=656-161
a=495