Consider the equation and its solution.
-15(x-[])=25
-15x+30=25
-15x=-5
x=1/3
what number should be in the empty box?
a. -30
b. -2
c. 2
d. 30

The correct answer is C. 2.

Step-by-step explanation:

To solve this problem, we should begin with the second step and work backwards in order to find the unknown value.  If given the equation -15x + 30 = 25, we should factor out a -15 to simplify.  This method is shown below.

-15x + 30 = 25

-15(x-2) = 25

We know this is correct because if we redistribute the -15 through the parentheses using the distributive property, we would get our original equation again.  In other words, this answer is confirmed by the fact that -15 * -2 equals positive 30.

However, we need to look closely at the question that is asked.  The box that we must fill in is already preceded by a negative sign, thus the correct answer is C. 2.

We can check our work by replacing the box with the number 2, getting -15(x-2) + 30 = 25, which was the equation we got earlier.

Hope this helps!