Byrnes Company currently produces and sells 4,000 units of a product that has a contribution margin of $6 per unit. The company sells the product for a sales price of $20 per unit. Fixed costs are $18,000. The company has recently invested in new technology and expects the variable cost per unit to fall to $8 per unit. The investment is expected to increase fixed costs by $15,000. After the new investment is made, how many units would have to be sold to breakeven?