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 as men wearing glasses. how many people are at the concert?

W = women
m = men

w = 3m (from the first sentence)

1/3w - 3/5m = 120
subsitute 3m for w
1/3(3m) - 3/5m = 120
m - 3/5m = 120
2/5m = 120
2m = 600
m = 300

back to the original equation
w = 3m
w = 3(300)
w = 900

900 women + 300 men = 1200 people.