To solve this, we will need to set up a system of equations. There are 2 units here: Tickets and money. We will need one equation for each unit. Let the more expensive ticket be x, and the less expensive ticket be y.
For tickets, we know that there were 200 total sold. That means that the total amount of tickets sold, x and y, is equal to 200. In equation form:
200 = x + y
For money, we know that total ticket sales were 1750 dollars. We also know that some tickets cost 10 dollars, while others cost 5 dollars. The sum of the products of each ticket cost and the amount of tickets sold will be equal to the total ticket sales. In equation form:
1750 = 10x + 5y
Now we have the system:
200 = x + y
1750 = 10x + 5y
To solve this system by substitution, isolate one of the variables in the first equation. I'll isolate x.
200 = x + y
200 - y = x
x = 200 - y
Substitute this expression (200 - y) for x into the second equation and solve for y.
1750 = 10x + 5y
1750 = 10(200 - y) + 5y
1750 = 2000 - 10y + 5y
1750 = 2000 - 5y
-250 = -5y
50 = y
Substitute 50 for y into either of the original equations to find x.
200 = x + y
200 = x + 50
150 = x
Lastly, substitute the x- and y-values into each original equation to check work.
200 = x + y --> 200 = 150 + 50 --> 200 = 200 --> True
1750 = 10x + 5y --> 1750 = 10(150) + 5(50) --> 1750 = 1500 + 250 --> 1750 = 1750 --> True
Answer:
150 of the more expensive tickets were sold.