Of 7,000 concert tickets, 80 tickets were not sold and of the ones tha

I'll try. Tell me if there is something specific you don't understand / agree with?

Usually, to calculate the revenue you'd divide the tickets into different price groups and multiply by the price per ticket in each group.
For example, if you had 5 tickets at $1 and 5 tickets at $2 then the revenue would be 1*5 + 2*5 = 15.

In this case, when you first read the question the instinct is to divide the tickets into 3 groups:
1) tickets that weren't sold. There are 80 of these and each generated $0 of revenue
2) 50% of the tickets that were sold. This is (7000 - 80)/2 = 3460 tickets. These were sold at "10% higher than the average price".
3) the other 50% of tickets that were sold - so another 3460 tickets. We have no information on the selling price of these tickets.

Creating an equation with the above 3 groups would give:
revenue = 80*0 + 3460*(average + 10%) + 3460*(unknown number)
Using this: "average price of the sold tickets is $10"
we can solve the above equation but it isn't fun.

Alternatively, we can divide all the tickets in the question into two groups:
1) this is the same as above - tickets that weren't sold. Each gives $0 of revenue.
2) all the tickets that were sold - a total of 6920 tickets. Each gives $10 on average of revenue.
So, our total revenue is 80*0 + 6920*10 = 69,200.

This is a trick question because the entire middle part of the prompt - "and of the ones that were sold, 50 percent were sold at 10 percent higher than the average price."
is useless and misleading. If the question were instead:
"Of 7,000 concert tickets, 80 tickets were not sold. If the average price of the sold tickets is $10 what is the total revenue?"
It would be much easier, wouldn't it?

Hope that helps!