At a concert, there are 3 times as many women as men. 3/5 of the men and 1/3 of the women wear glasses. there are 120 more women wearing glasses than men wearing glasses. how many people are at the concert?

Let us assume that the number of men at the concert = M
The number of woman in the concert = W
In the given problem, it is already told that there are 3 times the number of men in the concert.
Then
W = 3M
M = W/3
Total number of men and women wearing glasses = 3M/5 + W/3
In the problem given, it is already told that there are 120 more women wearing glasses than men
Then,
3M/5 +120 = W/3
3M/5 + 120 = M
M - 3M/5 = 120
(5M -3M)/5 = 120
2M/5 = 120
M = 600/2
   = 300
Number of Women in the concert = 3M
                                                       = 3 * 300
                                                       = 900
Then the total number of people in the concert = 300 + 900
                                                                           = 1200