If the bulb is in series with something else, then . . .
-- The brightness of the bulb depends on the <em>other</em> device in the circuit.
-- If the other device is designed to use <em>less power</em> than the bulb, then the
other device gets <em>more power</em> than the bulb gets.
-- If the other device is designed to use <em>more power </em>than the bulb, then the
other device gets <em>less power</em> than the bulb gets.
-- If the other device is removed from the circuit, then the bulb doesn't light at all.
This description of the often-screwy behavior of a series circuit may partly explain
why the electric service in your home is not a series circuit.
It would be helpful if you draw the figure of the problem. You will see that a right triangle would be constructed by the problem where 19.0 is the angle between the hypotenuse and the base of the triangle. It is said that the force acting is said to be 9.0 N at the said angle to the horizontal. Using trigonometric relations,
cos 19 = adjacent / hypotenuse = horizontal component / 9
horizontal component = 8.51 N