Question

At the movie theatre, child admission is $5.10 and adult admission is $8.70. On Saturday, 149 tickets were sold for a total sales of $1065.90. How many adult tickets were sold that day?

Answer 1

`a=85`

Explanation:

We can write the following system of equations:

`\begin{cases}5.10c+8.70a=1065.90\\c+a=149\end{case}`, where
`c` represents the number of child tickets sold and
`a` represents the number of adult tickets sold.

Multiplying the second equation by
`-5.10` and adding both equations lets us isolate and solve for
`a`:

`\begin{cases}5.10c+8.70a=1065.90\\-5.10c-5.10a=-759.9\end{case}\\3.6a=306,\\a=\fbox{$85$}`.