Fixed cost are variable per unit, while variable cost are fixed per unit. comment

Fixed costs do not change within the relevant range of production. As long as the production volume remains within the relevant range,

 the total amount of fixed costs does not change with a change in production volume. 

However, the cost per unit decreases as production increases and increases as production decreases. 

whereas

The per unit variable cost remains unchanged as production increases or decreases 

while total variable cost increases as production increases and decreases as production decreases.