`a) 60 - 26,75 - 13,25`
`= 60 - ( 26,75 + 13,25)`
`= 60 - 40`
`= 20`
--------------------------------
`b) 38,25 - 18,25+ 21,64- 11,64+ 9,93`
`= ( 38,25 - 18,25) -+( 21,64 - 11,64) + 9,93`
`= 20 +10 + 9,93`
`= 30 + 9,93`
`= 39,93`
--------------------------------
`c)45,28+52,17-15,28-12,17`
`= ( 45,28 - 15,28) + ( 52,17 - 12,17)`
`= 30 + 40`
`= 70`
--------------------------------------
`d) (72,69+18,47) - (8,47+22,69)`
`= 72,69 + 18,47 - 8,47 - 22,69`
`= ( 72,69 - 22,69) + ( 18,47 - 8,47)`
`= 50 + 10`
`= 60`
------------------------------------------
`e) 64 xx 23 + 37xx23-23`
`= 64 xx 23 + 37 xx 23 - 23 xx 1`
`= 23 xx ( 64 + 37 - 1)`
`= 23 xx100`
`= 2300`
