Question

Aflati trei numere naturale a,b si c care verifica simultan , egalitatiile:
a+b=80
a+c=90
b+c=100

Answer 1

scazi primele 2 ecuatii c-b=10
c-b=10
c+b=100
adunam aceste ecuatii si obtinem 
2c=110
c=110/2
c=55
a=90-c=90-55=35
b=100-c=100-55=45