a = #number of adults
b = #number of childs
Dawn: A group of 19 people are going to an amusement park
a+b = 19
Dawn: Adult tickets cost $39.50 each and child tickets cost $27.25 each
a*39.50
b*27.25
Dawn: If the total cost for admission to the park is $652.50
a*39.50+b*27.25=652.50
[input]solve(19=a+b, a*39.50+b*27.25=652.50)[/input]
solve this two equations by hand:
19=a+b
a=19-b
a*39.50+b*27.25=652.50
(19-b)*39.50+b*27.25=652.50
-b*39.50+b*27.25=652.50
-b*39.50+b*27.25=652.50-19*39.50=-98
b*(-39.50+27.25)=-98
b*(-12.25)=-98
b=-98/(-12.25)=8 =>
a=19-b=11 adults: 11
childs: 8
test:
[input]11*39.50+8*27.25[/input]
+3146 
