Total costs can be calculated in the Cost-Volume-Profit (CVP) graph
Total Cost = Fixed Cost (FC) + Variable Cost (VC)

Fixed Cost (FC) is constant as volume increases and is therefore a straight horizontal line at the fixed cost value on the y-axis. E.g. Fixed Cost (FC) = R 8 000.

Variable Cost (VC) however increases by the variable cost per unit with every successive unit that is produced. To calculate the Variable Cost/unit you will need to divide the Variable Cost by the units produced. The variable cost curve is therefore straight-line graph starting at the origin and with a gradient that is the variable cost per unit. E.g. Variable Cost (VC) = 8Q.

To determine Total Costs from a Variable Cost curve is given on the graph, you need to calculate the Variable Cost/unit by taking any point on the curve and finding the corresponding volume and costs. If you are given the breakeven point of 2000 units you will follow the 2000 units to the corresponding figure on the Variable Cost curve, R16 000. You will then divide the cost of R16 000 by the 2000 units to get R8/unit.

Now that you have the Fixed Cost and Variable Cost per unit you can determine the Total Cost.

Now Total Cost (TC) = Fixed Cost (FC) + Variable Cost (VC)

Fixed Costs are R8 000, Variable Costs are R8/unit and Quantity(Q) = 2000 units

Therefore:

TC = R8000 + 8Q
TC = R8000 + 8(2000)
TC = R24 000