The first sequence rule is add 4 starting from 15. The second sequence rule is add 3 starting from 18. What is the first number that appears in both sequences?

given the equation is 8+9z=-6, the first step would be to subtract the 8 from both sides:

8+9z-8=-6-8

since 8 minus 8 = 0, this would cancel out the 8. and since -6 minus 8 equals -14, the equation would look like this

9z = -14

yes, i think so although i am not sure. this is a very strange question.