$$\begin{array}{cc}\hfill \mathrm{\text{single integral}}\hfill & \hfill \int x\int M\int \frac{x}{o}\int \frac{A}{o}\int \frac{x}{A}\int \frac{A}{M}\int \frac{.}{\mathrm{\text{'}\text{'}}}\hfill \\ \hfill \mathrm{\text{double integral}}\hfill & \hfill \int \int x\int \int M\int \int \frac{x}{o}\int \int \frac{A}{o}\int \int \frac{x}{A}\int \int \frac{A}{M}\int \int \frac{.}{\mathrm{\text{'}\text{'}}}\hfill \\ \hfill \mathrm{\text{double nested integral}}\hfill & \hfill \int \int x\int \int M\int \int \frac{x}{o}\int \int \frac{A}{o}\int \int \frac{x}{A}\int \int \frac{A}{M}\int \int \frac{.}{\mathrm{\text{'}\text{'}}}\hfill \end{array}$$