subtract 51,550 and 28,600. 0 - 0 = 0 then 5-0=5 5-6 you can not do so you barrow from the 1. 1 becomes 0 and 5 becomes 15. 15-6=9. 0-8 you can not do so you need to borrow from the 5. 5 becomes 4 and 0 becomes 10. 10-8=2. Finally, 4-2=2. Put is all together and you have 22,950.