I have been asked a question regarding inconsistency. How would I use these equations to solve the questions?

x-y=5
2x = 2y+14

If you arrange your second equation this way
2x - 2y = 14 then divide by 2 you get
x-y=7

compare this with your first equation

You are looking at two lines which are parallel, and therefore can never intersect.

This is what makes the two equations "inconsistent"