Hey there! :)
x + 4/9 = 3/4
If you switch the equation around, it becomes: 3/4 - 4/9 = x
(Remember that the sign changes when moved to the other side)
Common multiple of 4 and 9: 36
3/4 = 27/36
4/9 = 16/36
27/36 - 16/36 = 11/36
Your answer is A. 11/36
Hope this helps :)