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
a+c = -5
c = -5 - a
b+c = -3
substitute
8-a + -5 -a = -3
3 - 2a = -3
-2a = -6
a = 3 you should be able to continue from here.......
+36916 
