Firstly we define the variables: $x_1$: Multiple of pancake recipe, $x_2$: Multiple of waffle recipe.
We want to maximize the total amount of serves. Therefore the objective function is
$$\text{max} \ \ 6x_1+5x_2$$
Next we have several constraints for the ingredients. For instance, that you have 24 cups of Bisquick. The corresponding constraint is
$$3x_1+3x_2\leq 24$$
If we use the double amount of the pancake recipe and three times of the waffles recipe we need $3\cdot 2+3\cdot 3=15<24$ cups of Bisquick. The constraint is fulfilled. You can call this constraint the Bisquick constraint. You make similar constraints for milk and eggs.
Finally we need the non-negativity constraint: $x_1,x_2\geq 0$. This real world problem requires that the variables are integers, but at the first step we can use the non-negativity constraint.
Update
The coefficients of the objective functions are negative in the table since it is a max problem. The first row is the objective function. For each $\leq$-problem we need a slack variable ($s_i)$.
$$\begin{array}{|c|c|c|c|c|c|c|c|c|c|c|} \hline \color{blue}{x_1}&x_2&s_1&s_2&s_3&RHS \\ \hline -6&-5&0&0&0&0 \\ \hline \color{red}3&3&1&0&0&24 \\ \hline 1&2&0&1&0&18\\ \hline 2&2&0&0&1&20\\ \hline \end{array}$$
This is the initial table. The pivot column is $x_1$ since $|-6|$ is larger than $|-5|$. Now we look for the minimum of the fractions of the RHS and the corresponding coefficients of colunm $x_1$.
$\min\left(\frac{24}{3},\frac{18}{1},\frac{20}{2}\right)=\min\left(8,18,10\right)=8$
That means the pivot row is the second row in the table. And therefore the first pivot element is $\color{red}3$.
