Lets look at each one:
A. 7x+x+8=16x
This left side will be 8x + 8, so its wrong.
B. x+x+1+1=2x+2
This left side will be 2x + 2, it is right!
C. 5(x+3)=5x+5
This left side will be 5x+15, so its wrong.
D. 9x−18=9(x+2)
This left side will be 9(x-2), so its wrong.
Our answer is going to be B) x+x+1+1=2x+2
x + x = 2x
1 + 1 = 2
2x + 2
I hope this helps! :)