Answer
$.75$
Work Step by Step
We are interested in the event $(E)$ that a new author is unsuccessful.
The sample size is $N=20$, (There are 20 new authors)
The frequency of $E$ is $fr(E)=15$ (There are 15 unsuccessful new authors)
The relative frequency of $E$ is $P(E)=\frac{fr(E)}{N}=\frac{15}{20}=0.75$