Use addition to rewrite the subtraction expression -2 - 9 without changing the digits. Do not solve.

Step-by-step solution

1. 1

   Identify the role of each symbol. The first minus is the sign of the number $2$; the second minus is the operation of subtraction acting on the positive number $9$. Only the operation and the sign of the second number are allowed to change.

2. 2

   State the rule. Subtraction is addition of the opposite:

   $a-b=a+(-b),$

   with $a=-2$ and $b=9$ here.

3. 3

   Take the opposite of the second number. The opposite of $+9$ is $-9$, so the operation becomes addition and the $9$ becomes negative:

   $-2-9=-2+(-9).$

4. 4

   Keep the brackets. Writing $-2+-9$ places two operation-like symbols side by side and is not standard notation; the parentheses around $(-9)$ make clear that the minus is a sign, not a second operation.

5. 5

   Confirm the two expressions agree. Starting at $-2$ and moving $9$ further in the negative direction lands on $-11$, and $-2+(-9)=-11$ as well. The requested rewrite is $-2+(-9)$.