For a particle to be in equilibrium,what must be the net force acting on it?

$A$ body under the action of several forces will have zero acceleration:

As shown in the figure,a $70\,kg$ garden roller is pushed with a force of $\overrightarrow{F} = 200\,N$ at an angle of $30^{\circ}$ with the horizontal. The normal reaction on the roller is $.......\,N$ (Given $g = 10\,m s^{-2}$)

What will be the tension produced in the string $PQ$ for the given system?

$A$ smooth cylinder of mass $m$ and radius $R$ is resting on two corner edges $A$ and $B$ as shown in the figure. The relation between the normal reactions at the edges $A$ and $B$ is

See the figure given below. $A$ mass of $6 \; kg$ is suspended by a rope of length $2 \; m$ from the ceiling. $A$ force of $50 \; N$ in the horizontal direction is applied at the midpoint $P$ of the rope,as shown. What is the angle the rope makes with the vertical in equilibrium (in $^{\circ}$)? (Take $g = 10 \; m s^{-2}$). Neglect the mass of the rope.