Peter R. answered 10/30/22
Experienced Instructor in Prealgebra, Algebra I and II, SAT/ACT Math.
A = No. adults; C = No. children's; S = No. student's tickets.
A + C + S = 1,200.
Also 15A + 10C + 8S = $11,200.
We are also told that S = 3(A + C) so S = 3A + 3C
Substituting in 1st eqn: A + C + 3A + 3C = 1200 → 4A + 4C = 1200
Substituting in 2nd eqn: 15A + 10C + 8(3A + 3C) → 15A + 10C + 24A + 24C → 39A + 34C = 11200
So we have a system of equations involving variables A and C: Using substitution method:
39A + 34C = 11200
4A + 4C = 1200. Divide by 4: A + C = 300, then A = 300 - C
39(300 - C) + 34C = 11200 → 11700 - 39C + 34C = 11200 →-5C = -500 → C = 100
A = 300 - 100 = 200
S = 1200 - A - C = 1200 - 200 - 100 = 900
Check: 15(200) + 10(100) + 8(900) = 3000 + 1000 + 7200 = $11,200