1.) x+3=18
the 1st thing that you must do is you have to put x by itself so you need to subtract 3 from 18 to even it out. Which is x=15 so that means that 15+3=18 which is true.
2.) x+3/4=2 1/4
the 1st things that you must do is you must get the x to be by itself so you need to subtract 3/4 by 2 1/4 to even it out. Which is x= 1 1/2 so that means that 1 1/2+3/4=2 1/4 which is true.