The previous briefing explained that accumulating resources are important.

So now we need to understand how to work out the result when it happens…

The following figure shows how to picture this idea. The box icon in the middle is the ‘tank’ containing the cash in your bank account, and the oval icons are the pumps, pumping cash in and out at some rate. If the inflow and outflow rates differ, as they do here, you know exactly how fast the resource ...