add or subtract the following decimal numbers.

[tex]1. 12.121 + 13.2219 + 9.123[/tex]
[tex]2. \: 9.3451 + 3.7321 + 6.2341[/tex]
[tex]3. \: 4.3562 + 2.6752 + 3.7852[/tex]
[tex]4. \: 0.6743 - 0.1235[/tex]
[tex]5. \: 15.7642 - 9.8964[/tex]
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