-x - 5y - 5z = 2
4x - 5y + 4z = 19
x + 5y – z = -20

Step-by-step explanation:

4x - 5y + 4z = 19

x + 5y - z = -20

5x + 3z = -1

-x - 5y - 5z = 2

x + 5y - z = -20

-6z = -18

z = 3

5x + 3(3) = -1

5x + 9 = -1

5x = -10

x = -2

-2 + 5y - 3 = -20

5y - 5 = -20

5y = -15

y = -3

x - 2, y = -3, z = 3

-2 which is choice A



Each time you move to the right 1 unit along the x axis, you will move 2 units down on the y axis along the diagonal line. 

The rise is -2 indicating a drop of 2 for each time the run is 1
rise/run = -2/1 = -2

An alternative is to use the slope formula m = (y2-y1)/(x2-x1) and you'll get the same answer. You can pick any two points on the line.