Question

sa se afle trei nr nat stiind ca doua cate doua au media aritmetica respectiv
a) 9
b)33
c)40

Answer 1

a+b=9⇒a=9-b
b+c=33 ⇒c=33-b
c+a=40 inlocuim in ultima  33-b+9-b =40⇒ 42-2b =40 ↑:2
21-b=20⇒21-20=b ⇒b=1 
atunci a=9-b=9-1=8 si c=33-b=33-1=32