If a + b = 8, b + c = 3, and a + c = 5, what is the value of the product abc?
a + b = 8 ⇒ b = 8 - a (1)
b + c = 3 (2)
a + c = 5 ⇒ c = 5 - a (3)
Sub (1), (3) into ( 2 )
8 - a + 5 - a = 3
13 - 2a = 3
-2a = 3 - 13
-2a = -10
a = 5
b = 3
c = 0
abc = 0
