The community theatre troupe was putting on a summer production of Shakespeare's
A Midsummer Night's Dream. Tickets for children
ages 12 and under were $5.50 each,
and tickets for everyone ages 13 and up were $7.50 each. The theatre troupe sold 30
tickets in the first hour of sales, for a total of $185. How many tickets for children 12
and under did they sell in that first hour?