Question

Determinati numerele naturale a,b,c ştiind că: a+b=90 b+c=110 a+c=100

Answer 1

a=90-b
c=110-b
a+c=200-2b, de unde rezulta 2b=100, de unde rezulta ca b=50; a=40; c=60

Answer 2

Facem sistem doua cate doua:
a+b=90    ⇒a=90-b
a+c=100  ⇒c-b=10

b+c=110   ⇒2b=110-10   ⇒b=50
c-b=10      ⇒c=10+b       ⇒c=60

a=90-b    ⇒a=40