Let's solve this system of linear equations using the addition/subtraction method.  Divide all 3 terms of the 1st equation by 5.  Combine the resulting equation with the 2nd given equation (2x+y=-8).  This will eliminate "x."
Now find y.  
Next, subst. your value of y into either of the original equations; find x.
Write your values for x and y as (x, y).  That's your "solution."