Answer :
- 5a - 12 < -18
Add 12 to each side:
-5a < -6
Divide each side by 5 :
-a < -1.2
a > 1.2
Add 12 to each side:
-5a < -6
Divide each side by 5 :
-a < -1.2
a > 1.2
[tex]-5a-12 < -18\ \ \ /+12\\\\-5a < -6\ \ \ \ /:(-5) < 0\ \then\ change\ " < " to\ " > "\\\\a > 1.2\\\\a\in(1.2;\ \infty)[/tex]