Let x denote the number of items produced and sold. The total revenue is
R (x) = 130 x

and the total cost is
C (x) = 50 x + 4400

where, now, ?=45. To find the break-even point we equate total cost to total revenue, so

C(x)=R(x)? 50 x+4400=130 x?80 x=4400
so that
x =55
Thus, the manufacturer has to sell at least 55 units to break even, i.e. no profit, or no loss.