Cost can be fixed or variable. Fixed cost remains constant regardless of the number of units. Some examples of fixed cost could be rent, property tax, and staff wages.
Variable costs are constant per volume.
The amount is the same for each unit regardless of the number of units that are produced. The break-even point is the point where the business neither makes a profit nor sustains a loss. This is the point where the net income is equal to zero. Total revenue line always starts at the origin because when there are no units there is no money. Use two points to draw this line.