Decimal tidy numbers pentgons

1.)9.7+8.6=18.3

   8.6-3=8.3

   9.7+3=10.0

   10.0+8.3=18.3

2.)32.7+8.9=41.6

   32.7-1=32.6

   8.9+1=9.0

   32.6+9.0=41.6

3.)9.7+8.6=18.3

   8.6-3=8.3

   9.7+3=10.0

   10.0+8.3=18.3

4.)3.4+19.7=23.1

   3.4-3=3.1

   19.7+3=20.0

   20.0+3.1=23.1