The total amount of money Mr. Haj used to pay for employee salary is 2/5*$4000 = $<<2/5*4000=1600>>1600
After paying the employee salaries, Mr. Haj remains with $4000-$1600 = $<<4000-1600=2400>>2400
He also uses 1/4*$2400= $<<2400/4=600>>600 on delivery costs.
The remaining amount of money that he uses to pay for orders is $2400-$600 = $<<2400-600=1800>>1800
#### 1800