What is the value of the current flowing through the galvanometer in the balanced condition of a Wheatstone bridge?

In the given circuit diagram,the currents $I_1 = -0.3\,A$,$I_4 = 0.8\,A$ and $I_5 = 0.4\,A$ are flowing as shown. The currents $I_2, I_3$ and $I_6$ respectively are

Current measured by the ammeter $(A)$ in the given circuit when no current flows through the $10\,\Omega$ resistance is . . . . . . $A$.

Write the necessary facts to understand Kirchhoff's laws.

The current flowing through the circuit shown in the figure is ............ $A$.

In a Wheatstone bridge (see figure),resistances $P$ and $Q$ are approximately equal. When $R = 400 \,\Omega$,the bridge is balanced. On interchanging $P$ and $Q$,the value of $R$ for balance is $405 \,\Omega$. The value of $X$ is close to ................. $\Omega$. (in $.5$)