Because X has the same numeric value (5) but opposite signs add the two equations together to eliminate X, then solve for y. Once you solve for Y you are able to solve for x:
5x - 6y = 6 + -5x +4y = -4
Combine like terms to get -2y = -8
Divide both sides by -2 to get y = 4
Now you have a value for y, replace y in one of the equations with 4 and solve for x:
5x - 6(4) = 6
5x -24 = 6
Add 24 to both sides:
5x = 30
Divide both sides by 5:
x = 6
The solution is (6,4)