Flatten for ListDensityPlot

How do I flatten a list of the form

{{{1, 2}, 3}, {{4, 5}, 6}, {{7, 8}, 9},...}

to put it in the form

{{1, 2, 3}, {4, 5, 6}, {7, 8, 9},...}

required to use ListDensityPlot? Thanks in advance for any help.