To find the median, put the numbers in order from least to greatest. So,
14, 16, 17, 18, 20.
Next, locate the central number. In this case, it's 17. 17 is your median number.
For the mean, add all of the numbers up and divide by how many there are. 14+16+17+18+20=85. There are 5 numbers, so 85/5=17. 17 is your mean number.