Solve the Equation: 75 - Triangle Symbol = 70

To solve the equation $75 - \triangle = 70$, we need to find the value of $\triangle$.

We start with the equation:

$75 - \triangle = 70$

Our goal is to solve for $\triangle$. To do this, we isolate $\triangle$ by rearranging the equation:

$\triangle = 75 - 70$

Next, we perform the subtraction on the right side:

$\triangle = 5$

Therefore, the numerical value of the triangle is $\triangle = 5$.

Thus, the correct answer is choice 4: $5$.