Hey there!!
We will have to solve this using 2 variables
Let's take the number of adults as ' x '
Let's the number of children as ' y '
The total number of tickets = 200
Let me explain this : If the total number of tickets is equal to 200, then the total number of people is equal to 200
Hence , x + y = 200
$9 for adults
The total cost for adult tickets = 9x
$6 for children
The total cost for children tickets = 6y
The total cost for these tickets = $1719
9x + 6y = 1719
3 ( 3x + 2y ) = 1719
3x + 2y = 573
...................................................................................................................................................
Now we have two equations
x + y = 200 ------------- ( 1 )
3x + 2y = 573 ---------- ( 2 )
Now let's multiply the first equation with 2
2 ( x + y ) = 2 ( 200 ) -------- ( 1 )
3x + 2y = 573
.......................
2x + 2y = 400
3x + 2y = 573
Now let's subtract the first equation from second
- ( 2x + 2y ) = - ( 400 )
3x + 2y = 573
..............................
-2x - 2y = - 400
3x + 2y = 573
x = 173
Hence , the number of adult tickets sold = 173
The required answer = 173
Hope my answer helps!
