Let the number of adult tickets sold be a and the number of child tickets sold be c.
Since the total number of tickets sold is 158, it follows that:
![a+c=158--------(1)](https://img.qammunity.org/2023/formulas/mathematics/college/s3ee3qsr2n2xbk4807thakz2fbebg1amol.png)
Since the total sales is $1,097.20, it follows that:
![9.80a+5.10c=1097.20----(2)](https://img.qammunity.org/2023/formulas/mathematics/college/f5lh1hrw676d70upoc5gdnw8ioh1svqa86.png)
From equation 1, isolate the variable c:
![c=158-a--------(3)](https://img.qammunity.org/2023/formulas/mathematics/college/a1obi6tr5yontus1bid3gqhnm5t1il8pk0.png)
Substitute equation 3 into equation 2:
![\begin{gathered} 9.80a+5.10(158-a)=1097.20 \\ 9.80a+805.80-5.10a=1097.20 \\ 9.80a-5.10a=1097.20-805.80 \\ 4.70a=291.40 \\ \text{ Divide both sides of the equation by }4.70: \\ (4.70a)/(4.70)=(291.40)/(4.70) \\ a=62 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/x2bixs4kj8nr0v4sokshi0ckk4wuotzxkx.png)
Therefore, the number of adults is:
62