High$-$low method

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

$\backslash$table$[[,$Total Costs,Units Produced$],[$January$,$$$191,520,2,660$ units$],[$February$,269,190,4,470],[$March$,297,920,6,460]]$

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 $