Fermat, Euler and Wilson · Easy problem

Fermat's Little Theorem gives $3 \cdot 3^{5} = 3^{6} \equiv 1 \pmod 7$, so $3^5$ is an inverse of $3$ modulo $7$. Find the inverse of $3$ modulo $7$: the integer $x$ with $0 \le x < 7$ and $3x \equiv 1 \pmod 7$.