diketahui 3x-2y = 15, 5x+4y = 3 dan 2x-5z = - 44 maka x+4y+z adalah

3x-2y = 15
5x+4y = 3 
2x-5z = - 44

eliminasi 

3x-2y = 15 x 2
5x+4y = 3   x1 
------------------

6x - 4y = 30
5x+ 4y = 3
----------------- +
11x = 33
x = 3

5x + 4y = 3
5 x 3 + 4y = 3
4y = 3 - 15
y = -12/4
y = -3

2x - 5z = -44
-5z = -6-44
-5z = -50
z = 10

x + 4y + z = 3 - 12 + 10
= 1