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