Question

Alexandra,Andreea si Adi au impreuna 1600 lei.Calculati ce suma are fiecare daca Andreea are cu 200 lei mai mult decat Adi,iar Alexandra are cat Andreea si Adi la un loc.

Answer 1

Nr de bani al Alexandrei = x
Al Andreei = y
al lui adi =z 
x+y+z=1600 lei
y=z+200 lei  
x=y+z
Deci inlocuim in ecuatie  
z+200 +z +z+200+z=1600
4z+400=1600
4z=1200
z=300
y=z+200=>y=300+200=>y=500
x=300+500=>x=800
x+y+z=1600=>800+500+300=1600=>1600=1600  

Answer 2

Al + An + Ad=1600
An=Ad+200
Al=An+Ad
Inlocuim in prima relatie
Ad+200 +Ad +Ad+200+Ad=1600 =>4Ad+400=1600 =>4Ad=1200 =>Ad=1200/4 =>Ad=300
An=Ad+200 =>An=300+200=500
Al=An+Ad =>Al=500+300=800