\begin{equation}\label{exintro2}
\underbrace{ce^A}_{\substack{\text{marginal cost} \\ \text{of effort}}} = \underbrace{R}_{\substack{\text{marginal expected} \\ \text{static return on effort} }} + \underbrace{\beta(R^A_x - R^A_y)e^{\mathcal{H}}}_{\substack{\text{marginal benefit from making} \\ \text{Bob switch approach}}}
\end{equation}
