Let $F:\mathbb R \to [0,1]$ be a distribution function of a probability measure $P$. This is,
$$F(x)=P((-\infty,x])$$
Then show that there is a random variable $X$, with
$$X : ((0,1],\mathcal B,\lambda)\to \mathbb R$$
(where $\mathcal B$ is the borel $\sigma $-algebra and $\lambda$ is Lebesgue measure), such that $P_{X}=P$$P_{X}=P.$