Use a proportion to find what number is 40% of 10y
so far i have
x/10y=40/100

I believe that what you would have to do is find 40% of 10 and then add the y. I got the answer 4y, but I'm not sure if that's what your looking for. Sorry if this isn't, hope I did help, even if it was a little :) 

29. because you will divide each number of months by 12 to find the number of years. which would mean, 5, 12.5, 16, 45, 50, 72.5. which is crazy. anyhow, i think you find the median in the middle. and yea hope your test goes good