solve this with explanation Please

it is all I have. teacher gave only this.

Task 2 The following shows the total overhead costs for given levels of a company's total output Cost Output S Units 20.000 5,000 40,000 7,000 55,000 10,000 if production is higher than 6000 units, variable cost per unit decrease by 10% a) What would be the variable overhead cost per unit (using the high-low) technique? I b) What would be the total cost per 2000 units