First off, let's take a look at what these numbers are:
Real numbers: It can be any numbers,both rational and irrational.
Natural numbers: The number has to be integer and positive.
Integers: A number without fraction or demical place.
Whole number: The number has to be natural and cannot be negative.
Therefore, as 12 is a positive number with no demical place or fraction, it is real numbers,integers, whole numbers, and natural numbers.
Hope it helps!
i read in class 4 but I don't explain the answer
we have

Group terms that contain the same variable, and move the constant to the opposite side of the equation

Factor the leading coefficient

Complete the square. Remember to balance the equation by adding the same constants to each side


Rewrite as perfect squares

-----> equation in vertex form
therefore
the answer is the option C

The first one shown, 400/2, is showing the point on the graph where she walks 400 ft in 2 minutes. In order to find the next proportion, you just have to look two minutes over which in this case is 800 ft for 4 minutes... written 800 over 4.