Hello,
First of all, you have to order the number from least to greatest:
7,6,12,19,6,13,16,20,9
6,6,7,9,12,13,16,19,20
We see that there are total 9 numbers. Median means that the middle number, so we separate 4 numbers into two groups
6,6,7,9
13,16,19,20. Now,we see that there is only one number which is 12. As a result, the median is 12. Hope it help!