How do you solve x + y = 1 and 3x – y = 11? Algebra Systems of Equations and Inequalities Systems Using Substitution 1 Answer Luke D. · Stefan V. Apr 11, 2018 #y=-2# and #x=3#. Explanation: You need to use simultaneous equations. Make #x# or #y# the subject from one equation and substitute it into the other. #x=1-y# Then #3(1-y)-y=11# #3-3y-y=11# #3-4y=11# #4y=-8# #y=-2# If #y=-2#, substitute back into either equation to find #x#. #x-2=1# #x=3# 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 4224 views around the world You can reuse this answer Creative Commons License