A and B
3000x + 24000 = 2400x + 30000
3000x - 2400x = 30000 - 24000
600x = 6000
x = 6000/600
x = 10 years A and B are the same
B and C
2400x + 30000 = 2000x + 36000
2400x - 2000x = 36000 - 30000
400x = 6000
x = 6000/400
x = 15 years B and C are the same
