Answer:
....we write a system
4x-5y+14=0
5x-4y+13=0
4x-5y=-14
5x-4y=-13
per combination:
-5(4x-5y=-14)
+4(5x-4y=-13)
-20x+25y=70
+20x-16y=-52
--->9y=18
--->y=18/9=2
we calculate x:
4x-5y=-14
4x-10=-14
4x=-14+10
x=-4/4=-1
solution(-1, 2)
we can calculate x-y:
-1-2=-3
--->x-y=-3
if the equations 4x - 5y + 14 = 0 and 5x - 4y + 13 = 0 are true simultaneously, then x - y is equal to -3.
Explanation: