Which of the following equations is true?

$1.$ Dollar sales for a segment to break even $=$ segment traceable variable expenses $/$

ssegment contribution margin ratio

$2.$ Dollar Sales For a segment to break even $=($ Segment tracebale fixed expenses$+$ segment allocated common fixed ecpenses$)/$ segment contribution margin ratio

$3.$ dollar sales for a segment to break even $=$ segment allocated common fixed expenses $/$ segmenet contribution margin ratio

$4.$ dollar sales for a segment to break even $=$ segment traceable fixed expenses $/$ segment contribution margin ratio