At an activity level of $8700$ units in a month, Falks Corporation's total variable $($TVC$)$ cost is $$728,190$ and its total fixed cost $($TFC$)$ is $$232,290.$ Calculate the following information at an activity level of $8900$ units in a month, assuming that this level of activity is within the relevant range:

a$.$ Variable cost per unit $($VCu$)$

b$.$ Total variable cost $($TVC$)$

c$.$ Fixed cost per unit $(FCu)$

d$.$ Total fixed cost $($TFC$)$