I have a doubt in a question regarding the high low method. The question is An organisation has the following total costs at 3 activity levels: Activity Level (units) 4,000 6,000 7,500 Total Cost $40,800 $50,000 $54,800 Variable cost per unit is constant within this activity range and there is a step up of 10% in the total fixed costs when the activity level exceeds 5,500 units. What is the total cost at an activity level of 5,000 units? I wanted to know how to calculate the 10% step up cost from total fixed cost.