Problem $4(20$ points$).$ A company has $10$ employees, each $of$ whom can work $onat$ most $2$ team projects. Six projects are under consideration. Each project requires $4$ out $of$ the $10$ workers. The required employees for each project and revenue generated from each project $is$ presented below.

Each worker who $is$ assigned $on$ any project must $be$ paid the retainer listed below.

Each worker $on$ a project $is$ also paid the project fee listed below.

Formulate $a(mixed-)integer$ linear optimization model $to$ maximize the net revenue for the company. Use computer tools $to$ find $an$ optimal solution $to$ this model.