Question

Mircea si Victoria au impreuna 77kg,Victoria si Alina au impreuna 65kg,iar Mircea si Alina au impreuna 74kg.Cate kg cantareste fiecare copil?

Answer 1

Notam cu m= nr  kg Mircea , cu v= nr kg Victoria si a=nr kg Alina
m+v=77kg
v+a=65kg
m+a=74kg
adunam prima si a treia relatie => m+v+m+a=77+74=> 2m+v+a= 151
dar stim ca v+a=65 => 2m + 65= 151 => 2m= 86 => m=43 
m+v=77 => 43+v=77 => v=34
m+a=74 => 43+ a= 74 => a=31