[tex]999+856-(456+1506)+9-28 = -126[/tex]

[tex]999 + 856 = 1855[/tex]
[tex]456 + 1506 = 1962[/tex]
[tex]1855 - 1962 = -107[/tex]
[tex]-107 + 9 = -98[/tex]
[tex]-98 - 28 = -126[/tex]