We have to solve the equation |6t - 9| - 21 =0

|6t - 9| - 21 =0

=> |6t - 9| = 21

This gives us two equations

6t - 9 = 21

=> 6t = 21 + 9

=> 6t = 30

=> t = 30/6

=> t = 5

And 9 - 6t = 21

=> -6t = 21 - 9

=> -6t = 12

=> t = 12/-6

=> t = -2

**Therefore we have t = -2 and t = 5**