Skill: Solve subtraction equations

A subtraction equation has an unknown number, often represented by $x$. To solve it, undo the subtraction by adding the same number to both sides. This keeps the equation balanced.

Example:

$$x-7=12$$

Step 1: Identify what is being subtracted.
The number $7$ is subtracted from $x$.

Step 2: Add $7$ to both sides to undo the subtraction:

$$x-7+7=12+7$$

Step 3: Simplify.
On the left, $-7+7=0$, so only $x$ remains:

$$x=19$$

Step 4: Check the solution.
Substitute $19$ for $x$ in the original equation:

$$19-7=12$$

This is true, so the solution is

$$\boxed{x=19}$$