I need to prove this plz help

$\displaystyle

A,B,C \ and\ D\ are\ non\ empty\ sets\ with\ \left|A\right|=\left|B\right| and\ \left|C\right|=\left|D\right| $

$\displaystyle

1. Prove\ that\ \left|A\times C\right|=\left|B \times D\right| $

$\displaystyle

2. \left|A^{n}\right|= \left|B^{n}\right|

$

$\displaystyle

3.\left|P\left(A\right)\right|=\left|P\left(B\righ t)\right|

$

With P i mean the power set

thx guys