Answer :
Let's call the highest score 'x'.
The scores in the crescent order would be:
20, 30, 50, 60, x.
So the median of those scores is 50.
If the mean and median are equal, we have that the mean is also 50, so we can find the value of x using:
[tex]\begin{gathered} 50=\frac{20+30+50+60+x}{5} \\ 250=20+30+50+60+x \\ 250=160+x \\ x=250-160=90 \end{gathered}[/tex]So the highest score is 90.