Voluntary contributions game: Two players $1$ and $2$ both own retail outlets in Kingston Mall. To boost sales, they are considering launching an advertising campaign. The advertising firm needs to be paid exactly $$100$ million in order to launch the campaign. If the advertising campaign is successfully launched, each player$$s sales will go up by $$60$ million.

The CEOs decide to fund the advertising campaign in the following way. Each CEO will simultaneously decide on an amount to contribute to the advertising campaign. Let CEO $1$s contribution be x$1($in million dollars$)$ and CEO $2$s contribution be x$2($in million dollars$).$