5,15,13,15,5,10,7,20,25,15. what is the median ? ?

Set them in order then start canceling out from both sides until you reach the middle .. so you'll have it like this: 5,5,7,10,13, 15,15 15,20, 25
then you cancel out 25 with 5 then 20 with the second 5 and so on until you end up with 13 and 15 in the middle with means you'll have to get their average  since you can't cancel them out . doing this you'll end up with 13+15/2 = 14 and that's your answer !

First arrange them in order from the smallest to the largest 
5,5,7,10,13,15,15,15,20.25
then the median will be 13 and 15
add them together then divide it by 2
13+15=28
28\2=14