Răspuns :
a+b+c=7980
1760+(1760+999)+c=7980
4519+c=7980
c=7980-4519
c=3461
1760+(1760+999)+c=7980
4519+c=7980
c=7980-4519
c=3461
a=1760
b=1760+999=2759
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a+b=1760+2759=4519
c=7980-4519=3461
b=1760+999=2759
-------------------------------
a+b=1760+2759=4519
c=7980-4519=3461