The equation which represents the people that want to visit the museum and the exhibit is 8n+5n. As you can see, the variable n is present in both terms 8n and 5n of the equation, so we can now factor the equation. You create parenthesis in which you put inside 8+5 and then you throw the variable n outside the parenthesis, and you get at last: 8n + 5n = (8+5)n