What is the formula for the objective function based on the following: Profit per unit for type $1$ is $$70$ and profit per unit for type $2$ is $$55.$ We want to maximize profit.

Multiple Choice

$$

$70x_1+55x_2$

$$

$70x_{1}55x_2$

$$

$70x_1-55x_2$

$$

$70x_{1}55x_2$