Answer:
1 : 1.5
Explanation:
If you say that there are 100 people in the audience, that means that 1% of the audience is 1 person. This means that the there are 60 people that are over the age of 60 and 40 that are under 60. So the ratio of under 60 to over 60 would be 40:60 which you can simply 1 : 1.5