대답: y = 1 x = 3 설명: # x + y = 4 # --- (1) # 2x-y = 5 # --- (2) (1)부터 # x + y = 4 # # x = 4-y # --- (3) 서브 (3)을 (2) # 2x-y = 5 # # 2 (4-y) -y = 5 # # 8-2y-y = 5 # # 8-3y = 5 # # 3 = 3y # # y = 1 # --- (4) 서브 (4) 내지 (3) # x = 4-y # # x = 4-1 # # x = 3 #
