If a+b+c=12, a+b=4, and a+c=7 what is the value of a ?
A
1
B
-1
C
3/23
D
2
Correct Answer: -1
a+b+c = 12 a+b = 4(Doing Subtraction), we get, c = 12-4 = 8Now, a+c = 7 a = 7-c = 7-8 = -1 (Ans)