Question

The equation -3x - 9 = -21 is solved as follows. Supply the correct numbers to complete the solution.

-3x - 9 = 21

-3x = _ Add 9 to both sides
x=_ Divide both sides by -3

Answer 1

Let's solve the equation step by step and fill in the blanks correctly.

Starting with the equation:

\[
-3x - 9 = -21
\]

The first step is to add 9 to both sides:

\[
-3x - 9 + 9 = -21 + 9
\]

This simplifies to:

\[
-3x = -12
\]

Now we divide both sides by -3:

\[
x = \frac{-12}{-3}
\]

This simplifies to:

\[
x = 4
\]

Now filling in the blanks:

1. The equation should read as \(-3x - 9 = \underline{-12}\).

2. The step "Add 9 to both sides" results in \(-3x = \underline{-12}\).

3. The division gives us \(x = \underline{4}\).

So the final filled in sentences will be:

-3x - 9 = -12

-3x = -12 (Add 9 to both sides)
x = 4 (Divide both sides by -3)