Answer :
c = children
a = adults
12c + 15a = 33456 (price)
c + a = 2450 (people)
c = 2450 - a (rewrite^)
12(2450 - a) + 15a = 33456 (substitute into the price equation)
29400 - 12a + 15a = 33456
3a = 4056
a = 1352
c = 2450 - (1352)
c = 1098
1098 children
1352 adults
a = adults
12c + 15a = 33456 (price)
c + a = 2450 (people)
c = 2450 - a (rewrite^)
12(2450 - a) + 15a = 33456 (substitute into the price equation)
29400 - 12a + 15a = 33456
3a = 4056
a = 1352
c = 2450 - (1352)
c = 1098
1098 children
1352 adults
[tex]x-\ number\ of\ children\\y-\ number\ of\ adults\\\\
\left \{ {{x+y=2450} \atop {12x+15y=33456}} \right. \\\\ \left \{ {{x=2450-y} \atop {12x+15y=33456}} \right. \\\\ substitution\ method\\\\
12(2450-y)+15y=33456\\\\29400-12y+15y=33456\\\\
29400+3y=33456\ \ \ \ | subtract\ 29400\\\\
3y=4056\ \ \ \ | divide\ by\ 3\\\\y=1352\\\\
x=2450-1352=1098\\\\
There\ were\ 1098\ children\ and\ 1352\ adults.
[/tex]