We can solve this by using systems of equations.
Let's find our first formula, how much money was made using the tickets.
Here x is how many child tickets we sold and y is how many adult tickets we sold. Now that we have defined that, we can make another formula for the total tickets sold!
since we sold 156 tickets that could be any combination of child and adult tickets.
Let's solve this system. I'm going to use <em>substitution</em> so I'm going to take our second formula and subtract both sides by x to get .
Now I will plug this in the first equation for y to get You plug it in for y to get
From this you can solve for x to get .
Since
There were 99 child tickets and 57 adult tickets.