Simplifying Algebra

Question 1:

x+x+x+x+x
5x

Question 2:

x+x+x
3x

Question 3:

2x+2x2x+4x
6x

Question 4:

5x4x2xx
-2x

Question 5:

3x+3y4x3y
x

Question 6:

3xz+2y5xz5y
-2xz-3y