Răspuns :
a + b = 120
b = a + 10
a + a + 10 = 120
2a = 120 - 10
2a = 110
a = 110 : 2
a = 55
b = a + 10
b = 55 + 10
b = 65
verificam
55 + 65 = 120
b = a + 10
a + a + 10 = 120
2a = 120 - 10
2a = 110
a = 110 : 2
a = 55
b = a + 10
b = 55 + 10
b = 65
verificam
55 + 65 = 120