Step 1- Solve for z in 4y - z =18 z = 4y - 18 Step 2- Substitute z = 4y - 18 into x + 2y - 5z = 40 x - 18y + 90 = 40 Step 3- Substitute z = 4y - 18 into 3x - y + z = 3 3x + 3y -18 = 3 Step 4- Solve for x in x - 18y + 90 = 40 x = 18y - 50 Step 5- Substitute x = 18y - 50 into z = 4y - 18 z = 4y - 18 Step 6- Substitute x = 18y - 50 into 3x + 3y - 18 = 3 57y - 168 = 3 Step 7- Solve for y in 57y - 168 = 3 y = 3 Step 8- Substitute y = 3 into z = 4y -18 z = -6 Final Answers- x = 4 y = 3 z = -6
