Simplifying Algebra

Question 1:

x+x
2x

Question 2:

x+x+x
3x

Question 3:

4x2x+xx
2x

Question 4:

2x2x+5x+3x
8x

Question 5:

x2y+5x5y
6x-7y

Question 6:

xz2y5xz+y
-4xzy