Solve Triangle + 79 = 80: Find the Symbol's Value

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

• Step 1: Rewrite the given equation by subtracting 79 from both sides.
• Step 2: Simplify the result to isolate and determine the value of the triangle $(\triangle)$.

Now, let's work through each step:
Step 1: We start with the equation $\triangle + 79 = 80$. To isolate $\triangle$, subtract 79 from both sides:
$\triangle + 79 - 79 = 80 - 79$.

Step 2: Simplify the result:
$\triangle = 1$.

Therefore, the numerical value of the triangle is $\triangle = 1$. This corresponds with choice 3.