Răspuns :
m + n = 110
n = m + 30
___________
m + m + 30 = 110
2m = 110 - 30
2m = 80
m = 80 : 2
m = 40
n = 40 + 30
n = 70
n = m + 30
___________
m + m + 30 = 110
2m = 110 - 30
2m = 80
m = 80 : 2
m = 40
n = 40 + 30
n = 70