Alex and Barry have a joint project. Each has first to decide whether to invest

$10$ or zero $($i$.$e$.,$ not to invest$)$ into the project. They make these individual

investment choices simultaneously. Once made, these investments are sunk. If

no$-$one invests, the project generates a total revenue of $0.$ If just one of them

invests, then the project generates a $($gross$)$ total revenue of $15.$ If both of

them invest, the project generates a $($gross$)$ total revenue of $30.$ Suppose that

both Alex and Barry are told how much the project has generated before they

make their $$share demands$$