#### Answer

Marcella worked for $11$ hours while Tim worked for $8$ hours.

#### Work Step by Step

1. Solve for $x$
Let $x = $ Marcella's working time on the room
(Tim's time) $+$ (Marcella's time) $= 19$
$(x - 3) + (x) =19$
$x - 3 + x = 19$
$2x - 3 = 19$
$2x = 22$
$x = 11$
2. Use $x$ to find each person's working time
Marcella $= 11$ hours
Tim $= (x - 3) = (11 - 3) = 8$ hours