So for a word problem I assume you must first define your variables. Ask yourself what is the question asking and how could the question be answered with what you know through relationships that the problem defines. For example if the problem says that the total of a few thing is a number put that in as one of your equations. Examine how relationships like if there is half the amount of variable A than variable B work and figure out how to write that as an equation that makes sense. To double check if you wrote your equations correctly double check the information given in the problem and mentally sound out the equation. Hope this helps and note there are as many equations as there are variables in your system.