+128408 3a + b + c = -3 (1)
a + 3b + c = 9 (2)
a + b + 3c = 19 (3)
Subtract (2) from (1) and we get
2a - 2b = -12
a - b = -6 ⇒ b = a + 6 (4)
Subtract (3) from (1) and we get
2a - 2c = -22
a - c = -11 ⇒ c = a + 11 (5)
Sub (4) and (5) into (1) and we get
3a + ( a + 6) + ( a + 11) = -3
5a + 17 = -3
5a = -3 - 17
5a = -20
a = -4
b = a + 6 = 2
c = a + 11 = 7
abc = (-4)(2)(7) = -56
