#### Answer

18

#### Work Step by Step

To find the missing term in the first equation, transform the second equation so that the left side is -2a.
$a\lt-9\longrightarrow$ multiply both sides by -2; reverse the inequality
$a\times-2\gt-9\times-2\longrightarrow$ multiply
$-2a\gt18$
The missing term is 18.