Answer:
The answers would be :
first table (equivalent to 8x ) = 2x-x+7x , 7x+x+0×y , 5(2x)-2x
second one (equivalent to 4x+3y) = 2x+2y+2x+y , 4x+4y-y
third one = every expression left but 2x+2y+2x .
you have to calculate them ! for example look at the first one ----> y+3x-y+9 is equivalent to 3x+9 'cause y-y = 0 ,so 3x +9 will be the left expression and you can't calculate it because the both left items in expression are not from the same type , one of them has a x but the other one doesn't have .
or for example the second one is 2x-x+7x and you know that -x can be written as -1x ,so it becomes like 2x+-1x+7x = 8x .
in the above example we could calculate numbers 'cause all of them have the same variable .
hope it was kinda helpful , sorry for bad english :D
ask me if you have further questions .