First lets break it down into these 2 equations: 2z - 9 = 1 and (-2z - 9) = 1
For the first equation its z = 5 and all u have to do is add 9 to both sides, add 1 + 9 to make it 10, then divide 10/2 to make it 5
For the second equation its z = 4 and all u have to do is simplify brackets, subtract 9 from both sides, subtract 1 - 9 so it can be -8, divide both sides by -2, two negatives make a positive so now -8/-2 is going to be 8/2, and lastly 8/2 is 4 since 2 * 4 = 8
Answers: z = 4, 5.