Răspuns :
3x+3y=150,3(x+y)=150,x+y=150:3=50
2(x-y)=40
x-y=40:2=20
x=20+y
20+y+y=50
2y=30
y=30:2=15
x=35
sau:x+y=50
x-y=20
2x=70
x=35
y=15
2(x-y)=40
x-y=40:2=20
x=20+y
20+y+y=50
2y=30
y=30:2=15
x=35
sau:x+y=50
x-y=20
2x=70
x=35
y=15
3x + 3y = 150
3 (x+y) = 150
x+y = 150:3=50
2(x-y) = 40
x-y=40:2=20
x=20+y
20+y+y=50
2y = 30y = 30:2=15
x = 35
3 (x+y) = 150
x+y = 150:3=50
2(x-y) = 40
x-y=40:2=20
x=20+y
20+y+y=50
2y = 30y = 30:2=15
x = 35