Algebra : the hair color of 39 males and females was recorded. thirteen of them had brown hair. eleven of them had blonde hair. five males had brown hair. four females had blonde hair. there were 21 females altogether.

The answer is below.

Males                                        females                       total
brown hair = 5                          = 8                               13
blonde hair= 7                          =4                                 11
other males=  6                        other females=  9              other total= 15     
total males= 18                   total females= 21               total for total in general is 39