Răspuns :
a + b = 23
a - b = 7
b = a - 7
a + a - 7 = 23
2a -7 = 23
2a = 23 + 7
2a = 30
a = 30:2 a= 15
a + b = 23
15 + b = 23
b = 23 -15 b = 8
a - b = 7
b = a - 7
a + a - 7 = 23
2a -7 = 23
2a = 23 + 7
2a = 30
a = 30:2 a= 15
a + b = 23
15 + b = 23
b = 23 -15 b = 8