Phillips Company manufactures air$-$conditioning units for commercial buildings and has noticed considerable variation in shipping expenses from month to month as per the data below:

Month Units Shipped Total Shipping Expense

January $4$ $ $1,960$

February $4$ $ $2,860$

March $5$ $ $2,300$

April $2$ $ $1,254$

May $3$ $ $2,010$

June $6$ $ $2,640$

July $8$ $ $3,744$

$13.$ Estimate variable shipping expenses to ship $12$ air conditioners if the shipping company reduces the variable cost per unit by $10\%$ for each unit shipped in excess of $10$ units.