splitting and re grouping in subtraction

1. Today my teacher gave us some work to do and they were splitting and grouping

this is a example of how it was done.

1. 18 +6 Splitting and regrouping in subtraction 20315     Jolie
   
   
   1. 18 +6
   = 10 + 8  + 6
   =  10 + 8 -6
   =10 + 2
   =12 ✔
   
   
   
   2. 19 - 7
   = 10 - 9 - 7
   = 10  + 9 -7
   = 10 +2
   =12 ✔
   
   
   
   3. 25 - 4
   =  20 -5+4
   =20+5-4
   =20+1
   =21 ✔
   
   
   4.38 - 6
   = 30 - 8+ 6
   =30 +8 -6
   = 30 + 2
   =32 ✔