Starting with this first equations up here, we see that we have 3x+4 equals smiley face. 3x has a 3 in it, but this is multiplied by x. A term like this, even though there is a number in it, is called a variable term. Because its whole value is going to change or vary depending on what number we plug in for x. This is definitely a variable term, 4 is just a number so no check there and finally, we have a smiley space. That means, it must be a variable. And we can go through the other three equations in the same way turn-by-turn to figure out what should be checked. And know that there are some things down here that we haven't talked explicitly about yet, and that might have thrown you off. Like, we have a fraction right here and we have a couple of expononents, but we'll get to those things pretty soon. And understanding the difference between variable and nonvariable terms is really important for understanding everything that we're going to do in Algebra. That means we're off to a great start in developing our foundation.