Factorise: ${\mathrm{a}}^2-1$ by using the identity: ${\mathrm{a}}^2-{\mathrm{b}}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$

Factorise:

$\left(x^2-2xy+y^2\right)-z^2$

Solve: $5-7x\ge 33$, where $x$ is an integer.

If one worker earns $₹ 200$ per day, how many workers can be employed within a monthly budget of $₹ 3$ Lakh?