50
1) Given that distribution, let's calculate the median.
20,30,40,50,60,70,80
2) As we have an odd number of observations, we can split that order this way:
20,30,40,50,60,70,80
As below 50, we have 3 observations, and above 50 we have 3 other observations. Then it's fair and right to say that the Median of that Distribution is 50.