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
