1. 2(x + y + z) -xz
2. 18× + 30y - (2x -y
3. ×-(2y-z)+8
4. 5x -(3×-7) + 2y
5. x² - (2y + z - 4)
6. 2xy-x³
7. x-{3x-[4×-(2×+11)]}