You need to solve the question so this means you need to work out the value of w. To work out the value of w you rearrange the terms and make w the subject of the equation.
Start with minusing 3w on both sides so that there is only ws on one side and adding 3 to both sides so that all the w are on one side and all the constants are on one side. This leaves us with 2w=18
As we want to know what the value of w and we know the value of 2w, we can divide both side by 2 and get the value of w which will mean w=9