Jessica and her family bought 5 tickets to a
music concert. Tickets for adults cost $5.10 and
tickets for children cost $3.60. Jessica and her
family spent a total of $21. How many tickets
for adults (a) and how many tickets for children
(c) did they buy?
a + c = 5
5.1a + 3.6C = 21
[?] adults [ ] children