1. 85-32=85-30-2=53
85-32=(80-30)+(5-2)=53
2. 68-26=68-20-6=42
68-26=(60-20)+(8-6)=42
3. 99-69=99-60-9=30
99-69=(90-60)+(9-9)=30
4. 74-34=74-30-4=40
74-34=(70-30)+(4-4)=40
