The manager at a concert venue keeps track of the number of adult tickets and student tickets sold each day and the total money received. on tuesday, a total of 89 tickets were sold, and the money collected was $1,119. if adult tickets are sold for $15 and student tickets are sold for $11, how many adult tickets and student tickets were sold?

A=number of adult tickets
s=number of student tickets

so
total of 89 tickets sold
a+s=89

total collected was 1119
15a+11s=1119

so we have
a+s=89
15a+11s=1119

subsitution
a+s=89
minus s from both sides
a=89-s

subsitte 89-s for a in the other equation

15a-11s=1119
15(89-s)+11s=1119
1335-15s+11s=1119
1335-4s=1119
minus 1335 from both sides
-4s=-216
divide both sides by -4
s=54

subsitute back
a=89-s
a=89-54
a=35

35 adult tickets
54 student tickets