To calculate the median: you want to organize all the numbers in it's data so it should look like this: 2, 5, 5, 8, 10, 12, 18, 20.
Now that it is organized look for the middle number so 9 is our median. I got this by adding 8 + 10 which equals 18 then dividing it by 2. So anytime you have 2 middle numbers add them then divide it by 2 it will always be your median.
To determine the mode: look for the number the occurs the most. I only see two 5's so the answer is 5 for our mode.
To determine the mean: Add all the numbers together then divide it by how many numbers there are so there are 8 numbers divide it by 8 after we add them.
2+5+5+8+10+12+18+20= 80 divide it by 8 and it equals 10. So 10 is the mean.