Y=5x-1 and y=3x+5.
Therefore 5x-1=3x+5, because both of those are equal to y and thus are equal to each other.
Subtract 3x from both sides: 5x-3x-1=3x-3x+5. This is the same as 2x-1=5.
Now add 1 to both sides. 2x-1+1=5+1. This is the same as 2x=6.
Divide both sides by 2. 2x/2=6/2. This is the same as x=3.
Substitute 3 for x in the two equations above and both yield the same answer, y=14.
For that pair of equations, x=3. y=14.