Use the following problem statement to answer questions $1-3.$

A real estate broker is responsible for selling homes in a new development. Ther will be two types of floor plans: Model $1$ and Model $2.$ Each Model $1$ will requir $0\mathrm{.}6$ acres of land, and each Model $2$ will require $1\mathrm{.}0$ acre of land. Twelve acres of land are available. The broker already has orders for three Model $1$ and four Model $2$ homes, and the contractor has requested that no more than $10$ Model homes be sold because of other circumstances. The broker also wants to use at most $130$ maple trees to landscape the development. Each Model $1$ and Model home will receive nine maple trees. The broker receives commissions of $$15,00$ to sell each Model $1$ home and $$8,000$ to sell each Model $2$ home. The broker wants to determine the number of Model $1$ and Model $2$ homes to maximize his contamissions. Formulate a linear programming model. $[$Note: $x1=$ the number $O$ Model $1$ homes. $x2=$ the number of Model $2$ homes$]$