Răspuns :
x+y=89
x=15+y =>
15+y+y=89.
2y=89-15
2y=74
y=74/2
y=37
x=y+15=37+15=52
y=37
x=52
x=15+y =>
15+y+y=89.
2y=89-15
2y=74
y=74/2
y=37
x=y+15=37+15=52
y=37
x=52