Heya Luinda.
To make the explanation easier, I will use a similar example but with simpler numbers. From there, hopefully it will become clear to you how to work out this problem.
Let's say there were 10 total tickets sold. Premier seats cost $2 and value seats cost $1. Total money earned was $14.
So the idea for these kind of questions is to write the statements as equations. Once we have all the equations, we can solve them to find out all the information we are looking for.
The first piece of information we have is that a total of 10 tickets were sold, and there were two different types of tickets, premier and value. That means that whatever the amount of premier tickets sold plus the amount of value tickets sold must add up to 10.
As an equation:
P + V = 10
where P is the amount of premier tickets sold and V is the amount of value tickets sold. The letters used as variables do not matter. You could also use x and y if you wish.
Now let's look at the next piece of information. We have the costs for the premier and value tickets and the total money earned.
How can you calculate the total money earned? Well, it would be the money earned from premier tickets plus the money earned from value tickets.
How do you find the money earned from premier tickets?
If there were one ticket sold, the money earned from premier tickets would be $2.
If there were two tickets sold, the money earned from premier tickets would be $2 + $2 = $2 × 2 = $4.
If there were three tickets sold, the money earned from premier tickets would be $2 + $2 + $2 = $2 × 3 = $6.
etc.
So we can see that if we take the price of the premier ticket and multiply it by the amount of premier tickets sold, that gives us the money earned from premier tickets. Or $2 × P (remember we chose P to represent number of premier tickets sold).
You can follow the same logic for value tickets and you get the money earned from value tickets is $1 × V.
Going back to the total money earned, we know that it is equal to the money earned from premier tickets + the money earned from value tickets.
Let's write it as an equation. We already know the total money earned is $14 and then let's create the variables Mp = money from premier tickets, and Mv = money from value tickets.
$14 = Mp + Mv
Furthermore, we know that money earned for each ticket equals price of the ticket times number of tickets sold for each type.
Or:
Mp = $2 × P
Mv = $1 × V
Let's substitute these values for money earned for each ticket into the equation with total money earned and make the equation simpler by removing the dollar signs:
14 = Mp + Mv
14 = 2P + 1V
Now we have two equations:
P + V = 10
14 = 2P + 1V
They both have P and V in them, which is good because we ultimately want to solve for P and V (since they represent the amount of premier tickets sold and value tickets sold). Generally, the way to do is is to find a way to write an equation with only one of the variables. Then solving for one variable is much easier.
Here we can do this by isolating one variable in terms of the other. Then we can use that to substitute in the other equation. It will be clearer once you see it in action:
P + V = 10
P = 10 - V
We just subtracted V from each side. Now we have P isolated and written in terms of V. So we can substitute this "value" of P into the other equation.
14 = 2P + 1V | This is the other equation unchanged
14 = 2(10 - V) + 1V | I replace P with (10 - V), the result from before
14 = 20 - 2V + 1V | Now we just solve for V
14 = 20 - V | Add V to both sides
V + 14 = 20
V = 6
Great, now we have one of the results we are looking for. the number of value tickets sold is 6. From here, we can substitute V = 6 into one of the equations to get P.
10 = P + V
10 = P + 6
4 = P
Cool, so now we have both the number of premier tickets sold and the number of value tickets sold.
If we want to double check, we can also substitute in P and V in the second equation to make sure everything adds up correctly.
14 = 2P + 1V
14 = 2(4) + 1(6)
14 = 8 + 6
14 = 14
Wonderful it does.
So from here, you should be able to do something similar for your problem.
Hope that was helpful. Let me know if you have any further questions.