Let's establish our unknown numbers with the variables x and y:
x amount of students
y amount of parents
We can establish these equasions:
x + y = 183 (number of students + number of parents)
2.50x + 4.25y = 538 (the amount each group paid)
To make things easier, we can put x or y from the first equasion on to the right side of that same equasion. I switched x in my case
![x + y = 183 \\ y = 183 - x](https://img.qammunity.org/2019/formulas/mathematics/high-school/ojtjrk87gwudd6ten5espmhzihxkakodyy.png)
We insert that into our second equasion and solve it
![2.50x + 4.25(183 - x) = 538 \\ 2.50x + 777.75 - 4.25x = 538 \\ 2.50x - 4.25x = 538 - 777.75 \\ - 1.75x = - 239.75 \\ x = ( - 239.75)/( - 1.75) \\ x = 137](https://img.qammunity.org/2019/formulas/mathematics/high-school/8ix0gkwruexxl9vhiqo7rzvndqd00krxyi.png)
We now know that x = 137. If the total is 183, we just have to subtract 137 from that number to find out the value of y
![183 - 137 = 46](https://img.qammunity.org/2019/formulas/mathematics/high-school/7tq7oy21v2lswm78aqcq7xaaqkq22hs356.png)
RESULT:
x = 137 ==> 137 student tickets sold
y = 46 ==> 46 adult tickets sold