5x - 4y + 2z :
5 (-8) - 4 (3) + 2 (-4)
-40 - 12 - 8
- 60
3x + 2 (x - 4) = 6x - 8 - x
3x + 2x -8 = 6x - 8 - x
5x - 8 = 5x - 8
Since both sides are equal, it has infinitely many solutions.
To find how many students chose flying, just add the numbers 26 and 12 to get 38 students.