Just like solving an equation except when we divide through by a
negative number we must reverse the direction of the inequality.
However, there is no occasion here to do that here, because when
we divide through by a positive number we DO NOT REVERSE the
inequality.

9 + 11C < 2(0.5C - 5)

9 + 11C < 2(0.5C) - 2(5)

9 + 11C < 1C - 10

Subtract 9 from both siade

    11C < 1C - 19

Subtract 1C from both siade

    10C < -19

Divide through by 10, which is a POSITIVE
NUMBER, so we DO NOT reverse the <.

   10C     -19
  ————— < —————
   10       10

Cancel the 10's on the left:

   1
   10C     -19
  ————— < —————
   10       10
   1


      C < -19/10

or

      C < -(1 9/10)

Edwin
AnlytcPhil@aol.com