The median salary for male workers for the years 1975-2006 can be modeled by the function thousand dollars, where x is the number of years from 1970. Find the minimum on the graph of this function between x = 10 and x =30 and interpret it.(Use the window [10, 30] by [40, 45] )

I know how to get the minimum, i just need help interpreting it. Thanks in advance ;D.