Alden Company's monthly data for the past year follow. Management wants to use these data to predict future variable

and fixed costs.

$1.$ Estimate both the variable costs per unit and the total monthly fixed costs using the high$-$low method. $($Do not round intermediate calculations.$)$

$2.$ Predict future total costs when sales volume is $($a$)375,000$ units and $($b$)415,000$ units.