ANSWER
475 adult tickets and 375 children tickets were sold
Step-by-step explanation
Let the number of adult tickets be a.
Let the number of children tickets be c.
The total number of tickets is 850. This means that:
![a+c=850](https://img.qammunity.org/2023/formulas/mathematics/college/l3ulmdu3hrepqz7lzkbwvnn66swpxqdkw6.png)
The cost of all the tickets sold is $1512.50.
Each adult's ticket sold for $2.00 and each children ticket sold for $2.00.
Therefore, we have that:
![2a+1.5c=1512.50](https://img.qammunity.org/2023/formulas/mathematics/college/okf4cpt4exl5jocrz98adjfolgtlwz1nvr.png)
We now have a system of two simultaneous equations:
![\begin{gathered} a+c=850 \\ 2a+1.5c=1512.50 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/p1eorx6s7esmommsmk92ysslzuqfo7wg2s.png)
From the first equation, make a subject of formula:
![a=850-c](https://img.qammunity.org/2023/formulas/mathematics/college/t2w3afueclcox35e7doi7c128hck9wd39n.png)
Substitute that into the second equation:
![\begin{gathered} 2(850-c)+1.5c=1512.50 \\ 1700-2c+1.5c=1512.50 \\ 1700-0.5c=1512.50 \\ \Rightarrow0.5c=1700-1512.50=187.50 \\ \Rightarrow c=(187.50)/(0.5) \\ c=375 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/y4znu8x6akpp6nx4l3xja9y51tei3f19u0.png)
Recall that:
![a=850-c](https://img.qammunity.org/2023/formulas/mathematics/college/t2w3afueclcox35e7doi7c128hck9wd39n.png)
This means that:
![\begin{gathered} a=850-375 \\ a=475 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/6rjm2kls9rpz4qtbu42gm490snw80o46gw.png)
Therefore, 475 adult tickets and 375 children tickets were sold.