`a) 8.24.6 + 12.4.52 + 2.22.24 `
`= 48.24 + 48.52 + 48.22`
`= 48. (24 + 52 + 22) `
`= 48.98`
`= 48.100 - 48.2`
`= 4704`
`b) 18.58.2 - 9.27.4 + 12.69.3 `
`= 36.58 − 36.27 + 36.69`
`= 36(58 - 27 + 69)`
`= 36.100`
`= 3600`
`c) 30.85.3 + 18.72.5 - 45.37.2 - 9.20.10`
`= 90.85 + 90.72 - 90.37 - 90.20`
`= 90.(85 + 72 - 37 - 20)`
`= 90.100`
`= 9000`