1. ## Help!

Notice that $x^{329} = \left( x^{30} \right)^{10} x^{29}\equiv x^{29} (\bmod 31)$
Also, $452 \equiv 18(\bmod 31)$.
Therefore, $x^{29} \equiv 18 (\bmod 31)$.
Multiply by $x$ to get $18x\equiv 1(\bmod 31)$