Answer
$\dfrac{1}{10}$ or $0.1$
Work Step by Step
We know that $\text{probability}=\dfrac{\text{number of favourable outcomes}}{\text{number of all outcomes}}=\dfrac{n(E)}{n(S)}.$
Here we have:
$20$ possible outcomes so $n(S)=20$
$2$ favorable outcomes ($100$ and $30$) so $n(E)=2$
Therefore,
$P\left(\text{spinning a 100 or a 30}\right)=\dfrac{2}{20}=\dfrac{1}{10}=0.1$