How do you solve x = y - 8 & -x - y = 0? Algebra Systems of Equations and Inequalities Systems Using Substitution 1 Answer José Roberto Pereira Oct 18, 2015 x=-4 y=4 Explanation: y=x+8 (1) y=-x (2) Subtracting (1) - (2): 0=2x+8 2x=-8 x=-8/2=-4 y=-(-4) =4 Answer link Related questions How do you solve systems of equations using the substitution method? How do you check your solutions to a systems of equations using the substitution method? When is the substitution method easier to use? How do you know if a solution is "no solution" or "infinite" when using the substitution method? How do you solve y=-6x-3 and y=3 using the substitution method? How do you solve 12y-3x=-1 and x-4y=1 using the substitution method? Which method do you use to solve the system of equations y=1/4x-14 and y=19/8x+7? What are the 2 numbers if the sum is 70 and they differ by 11? How do you solve x+y=5 and 3x+y=15 using the substitution method? What is the point of intersection of the lines x+2y=4 and -x-3y=-7? See all questions in Systems Using Substitution Impact of this question 1551 views around the world You can reuse this answer Creative Commons License