Solve Symbol Addition: Finding ○ + 21 When ○ = 7

To solve this problem, we'll follow these steps:

• Step 1: Identify the number represented by the symbol $\circ$.
• Step 2: Substitute the symbol $\circ$ with the number 7.
• Step 3: Perform the addition of 7 and 21.

Now, let's work through each step:
Step 1: Identify $\circ = 7$ from the problem statement.
Step 2: Substitute the value 7 for $\circ$ in $\circ + 21$, so we have $7 + 21$.
Step 3: Add 7 and 21 to get 28.

Therefore, the solution to the problem is $28$.