Answer:
Putting the value in x = 2 , y =4 in 2x - 2y we get,
2 × 2 - 4× 2= 4-8 = -4
Putting the value in z = 3 in z - 5 we get,
z - 5 = 3 - 5 = -2
In the given question, the options are related to linear pair .
And according to linear pair, if a line cuts another line at a point, then the sum of the adjacent angles formed at that point is 180 degree.
Therefore, from the given diagram we can say that, angles WXY and YXZ are linear pair, so there sum have to be 180.

And the correct option is the third option .
2.7 gallons.
Since the tank is already 4/5 full, only 1/5 is needed to fill it completely. As 13.5 gallons represent 5/5 (the full tank), you can take 13.5 divided by 5 to find 1/5.