Respuesta :

Apocrophon
So a is the number of adult tickets and s is the number of student tickets

a+s=180
$4a + $2.5s = $645

a+s=180
a=180-s

4a+2.5s=645
4(180-s)+2.5s=645
720-4s+2.5s=645
720-1.5s=645
75-1.5s=0
1.5s=75

s=50

a+s=180
a+50=180

a=130