Question

Trei copii, Andrei, Barbu si Calin, au impreuna 22 mere. Aflati cate mere are fiecare dintre ei, stiind ca Barbu are de doua ori mai multe decat Andrei, iar Calin are cu 3 mere mai putin decat Barbu.  
AJUT-TI-MA, VA ROG!!
Vreau rezolvarea completa, multumesc anticipat!

Answer 1

A+B+C=22
B=2A
C=2A-3
A+2A+2A-3=22
5A-3=22
5A=25
A=5 mere
B= 5*2 = 10 mere
C = 10-3 = 7 mere :D

Answer 2

$\hbox { Scrii ecuatia generala: } A+B+C=22$
$B=2A$
$C=B-3$ ⇒ $C=2A-3$

$\hbox { Introduci in ecuatia principala: }$ $A+2A+2A-3=22$

$5A=25$ ⇒ $\boxed { A=5 } \hbox { Andrei are 5 mere }$

$B=2A$ ⇒ $\boxed {B=10}$ $\hbox { Barbu are 10 mere }$

$C=B-3$ ⇒ $C=10-3$ ⇒ $\boxed {C=7}$ $\hbox { Calin are 7 mere }$