Answer:
Take the second equation and add 4 to both sides, this gives you x=y+4. The plug in y+4 on the first equation, so y=-(y+4)-6, distribute the negative to everything inside the parentheses, and you get y=-y-4-6. Combine like terms and you get y=-y-10, then add y to both sides, you get 2y=-10, divide both sides by 2 and you get y=-5.
Then plug -5 into the second equation and you get -5=x-4, add 4 to both sides and you get -1=x.
If you want to check your answer, just plug in x and y to either of the equations and see if it makes a true statement.