Which it true about modeling a solution to an addition problem on a vertical number line? a. when adding a negative number, you move down b. when adding a positive number, you move down c. locating the sum is not necessary. d. locating the sum is the first step

Step-by-step explanation:

Actually, according to transformation of functions, there's two types of transformation, those that only involve translation, and those that change the dimension of the function.

In this case, modelling a solution to an addition problem, we know that adding a negative number, the function will move downs, because in that case we will be transformation or "changing" the y-variable, that's why it will move vertically.

Therefore, the right answer is A.

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