For question one, "three less than a number" means "n – 3," and "is –6" means that the equation is set to/is equal to –6. So, your final answer will be n – 3 = –6.
For question two, consider the fact that the total must be more than or equal to 200 dollars. So, you'll use the "more than" sign with the line under it. "d" represents the amount of dollars you need in addition to the $135 that she starts out with, so your answer will be B.
For question three, all you need to do is input the four x values you've been given into the equation. If you get the corresponding y value for that x value, the point will be on the graph. If the equation equals something different than the y value you've been given, it's not a point on the graph. Based on this, your answer is B.
For question four, you can solve the equation with the y value set to 0. This will get you 6 for the x value, making your answer A.
For question five, if you look at the graph you've been given, you can see that the x values stretch on forever, as the arrows indicate. However, the y values stop at –3 and can't go down any further than that point. Your answer is A.
For question six, the slope of a vertical line will always be zero. You could solve for the slope if you want, but it will always be zero, just as a horizontal line will always be undefined (since the numerator will always be divided by zero when finding the slope of a horizontal).
For question seven, a discrete scenario doesn't contain any fractional parts of the material being measured. The amount of people in a family cannot be fractional, while the water in a pool and the height of a plant can. Also, another thing to remember is that discrete data doesn't require a measuring device, such as a ruler or scale, while continuous data does.
I know you already got your answers, but I hope this helped you out anyways! :-)