x+y+z=5 x+y=6 y+z=4 In the solution of the equations above, y=? A.1 B.2 C.3 D.4 E.5?

x + y + z = 5
x + y = 6
y + z = 4
x + 2y + z = 10
y = 5
x = 1
z = -1
Answer choice:
E.5

x + y + z = 5 ..... [1]
x + y = 6 ...... [2]
y + z = 4 ...... [3]

[2] + [3] :
x + 2y + z = 10 ...... [4]

[4] - [1] :
y = 5

...... The answer is : E. 5

subtracting the second equation from the first gives
z=-1
plug that in the last equation and get
y+(-1) = 4, so
y=5.