We have two cost functions.
Company A charges a fixed value of $90 and a variable cost of $9 per sq yd.

Company B chargesa fixed value of $50 and a variable cost of $13 per sq yd.

The breakeven point for the square yard of the floor, when both cost are the same, can be calculated as:

The breakeven point is x=10 sq yd.
If x>10, company B is more expensive that company A.