High$-$Low Method

The manufacturing costs of Rosenthal Industries for the first three months of the year follow:

$\backslash$table$[[,$Total Costs,Production$],[$January$,$$$306,180,1,215$ units$],[$February$,352,110,2,360],[$March$,476,280,3,915]]$

Using the high$-$low method, determine $($a$)$ the variable cost per unit and $($b$)$ the total fixed cost.

a$.$ Variable cost per unit

$

b$.$ Total fixed cost

$