Problem $4-18$ Cost$-$Volume$-$Profit Analysis; Degree of Operating Leverage $[$LO$1,$ LO$3,$ LO$4,$ LO$5,$ LO$8]$

Feather Friends, Incorporated, distributes a high$-$quality wooden birdhouse that sells for $$20$ per unit. Variable expenses are $$10$ per unit, and fixed expenses total $$220,000$ per year. Its operating results for last year were as follows:

$\backslash$table$[[,],[$Sales units$),$$$560,000$