Answer :
Ok ready here we go
-2a-9=6a+15
+2a. +2a
-9=8a+15
-15. -15
-24=8a
-24/8=a
Good luck
[tex]-2a-9=6a+15\ \ \ \ \ |add\ 9\ to\ both\ sides\\\\-2a=6a+24\ \ \ \ \ \ |subtract\ 6a\ from\ both\ sides\\\\-8a=24\ \ \ \ \ \ |divide\ both\ sides\ by\ (-8)\\\\\boxed{a=-3}[/tex]
