State and prove ampere's law ?

Statement : The line integral of the intensity of magnetic induction field around any closed path is equal to ${\mathrm{\mu }}_{\mathrm{o}}$ times the net current enclosed by this path. $\text{ i.e ∮}\overrightarrow{\mathrm{B}}\cdot \overrightarrow{dl}={\mathrm{\mu }}_0\mathrm{i}$
Let a closed plane curve encloses currents i₁, i₂, i₃ and i₄ through the conductors as shown in

${\mathrm{i}}_1\otimes ,{\mathrm{i}}_4\otimes -\text{ currents down ward +ve }$ 
${\mathrm{i}}_2\odot ,{\mathrm{i}}_3\odot \text{ - cruurents upward -ve }$
The net current through conductor is $\mathrm{i}={\mathrm{i}}_1-{\mathrm{i}}_2-{\mathrm{i}}_3+{\mathrm{i}}_4$
The magnetic induction along the closed path is $\text{∮}\overrightarrow{\mathrm{B}}\cdot \overrightarrow{dl}={\mathrm{\mu }}_0\mathrm{i}$