Let a represent adult tickets
Let s represent student tickets
3.50 a + 2.50 s = $937.50 eqation 1
three hundred twenty one tickets were sold altogether
a + s = 321 equation 2
s= 321 - a
we replace it in equation 1 so
3.50a + 2.50s = 937.50
3.50a + 2.50(321-a)=937.50
3.50a+802.5-2.50a=937.50
3.50a-2.50a+802.5=937.50
1.00a+802.5=937.50
a=135
and s=321-135= =186
