Solve the Equation: Finding the Value of △ in 78 + △ = 80

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

• Recognize the format of the provided equation.
• Apply the appropriate arithmetic operation to isolate $\triangle$.
• Perform the necessary calculations.

Now, let's work through each step:
Step 1: The given equation is $78 + \triangle = 80$. We are tasked with finding the value of $\triangle$.
Step 2: To find $\triangle$, rearrange the equation to solve for $\triangle$:
$\triangle = 80 - 78$.
Step 3: Subtract the known value from the total to isolate $\triangle$:
$\triangle = 80 - 78 = 2$.

Hence, the solution to the problem is $\triangle = 2$.