It costs 3$ for an adult and 2$ for a student to attend a car show. 250$ was collected when 90 people attended how many were adults and how many were students
a + s = 90 so a = (90-s)
3 a + 2 s = 250
so
3(90-s) + 2 s = 250
etc
3 a + 2 s = 250
so
3(90-s) + 2 s = 250
etc