Subtraction using addition

 

subtraction with adding

4531
3726
====
add 3 to both items. 6 and 3 makes 9
4534
3729
====
add 70 to both items. 70 and 20 makes 90
4604
3799
====
add 200 to both items. 700 and 200 makes 900
4804
3999
====
====
result 804 + 1 = 805