Răspuns:
[tex]\displaystyle Al \ \ treilea \ numar \ = > c\ = \ \boxed { 32,8}[/tex]
Explicație pas cu pas:
[tex]\displaystyle \frac{a\ + \ b \ + c }{3} = \ 21,6 \\\\ \displaystyle a \ + b \ + \ c \ = \ 21,6 \ \cdot \ 3 \\ \\ \displaystyle a\ + \ b\ + \ c \ = \ 64,8 \\\\Daca \ a \ + \ b\ = \ 32\ , \ atunci : \\\\ \displaystyle 32 \ + \ c \ = \ 64,8\\\\ \displaystyle c \ = \ 64,8\ - \ 32 \\\\ \displaystyle c\ = \ \boxed { 32,8}[/tex]
