A theater has a seating capacity of 1050 and charges $5 for children, $7 for students, and $9 for adults. At a certain screening with full attendance, there were half as many adults as children and students combined. The receipts totaled $7650. How many children attended the show?
so adults were 1/3 and young people were 2/3
(9 * 350) + [7 (700 - c)] + 5 c = 7650
Let's break down the problem step by step:
Step 1: Let's represent the number of children as C.
Step 2: Since there were half as many adults as children and students combined, the number of adults would be (C + S) / 2.
Step 3: The number of students can also be represented as S.
Step 4: The total number of people attending the screening would be C + S + (C + S) / 2, which equals 1050 (the seating capacity of the theater).
So, we can write the equation as:
C + S + (C + S) / 2 = 1050 ............ (Equation 1)
Step 5: The total receipts from the screening totaled $7650.
The income from children would be 5 * C.
The income from students would be 7 * S.
The income from adults would be 9 * ((C + S)/2).
So, we can write the equation as:
5C + 7S + (9 * (C + S)/2) = 7650 ............ (Equation 2)
Now, we have two equations (Equation 1 and Equation 2) with two variables (C and S). We can solve them simultaneously to find the values of C and S.
To solve this problem, we need to set up a system of equations.
Let's denote:
C = number of children
S = number of students
A = number of adults
We know that the theater has a seating capacity of 1050, so the total number of people who attended the show is C + S + A. According to the problem, this must equal 1050:
C + S + A = 1050 ........ Eqn 1
We are also given that there were half as many adults as children and students combined:
A = 1/2 * (C + S) ........ Eqn 2
Finally, we know that the total receipts added up to $7650:
5C + 7S + 9A = 7650 ........ Eqn 3
Now, we have a system of three equations with three variables (C, S, and A). We can solve this system by substitution or elimination method.
Let's use the substitution method. We'll solve Eqn 2 for A and substitute it into Eqn 3.
From Eqn 2:
A = 1/2 * (C + S)
Substituting this into Eqn 3:
5C + 7S + 9 * (1/2 * (C + S)) = 7650
Simplifying this equation:
5C +7S + (9/2)C + (9/2)S = 7650
(19/2)C + (23/2)S = 7650
Now, we can multiply both sides by 2 to remove the fractions:
19C + 23S = 15300 ........ Eqn 4
We have two equations now, Eqn 1 and Eqn 4. Let's solve this system.
Eqn 1: C + S + A = 1050
Eqn 4: 19C + 23S = 15300
To solve the system, we can either use substitution or elimination. I will use the elimination method in this case.
Multiplying Eqn 1 by 19:
19C + 19S + 19A = 19950
Now we can subtract Eqn 4 from this new equation:
19C + 19S + 19A - (19C + 23S) = 19950 - 15300
19C + 19S + 19A - 19C - 23S = 4650
-4S + 19A = 4650 ........ Eqn 5
Now we have a system of two equations:
Eqn 4: 19C + 23S = 15300
Eqn 5: -4S + 19A = 4650
We can now solve this system of equations to find the values of C and S.
To do this, let's multiply Eqn 5 by 23:
-4S + 19A = 4650
-92S + 437A = 106950 ........ Eqn 6
Now, let's add Eqn 4 and Eqn 6 together:
19C + 23S = 15300
-92S + 437A = 106950
To eliminate the S terms, we need to multiply Eqn 4 by 92 and Eqn 6 by 19:
92(19C + 23S) = 92(15300)
19(-92S + 437A) = 19(106950)
After simplification, we get:
1756C + 2126S = 1412400
-1748S + 8293A = 2032050
Now we have a system of two equations in terms of C and A:
Eqn 7: 1756C + 2126S = 1412400
Eqn 8: -1748S + 8293A = 2032050
Now we can use substitution or elimination to solve for C and A. I'll use the elimination method.
Let's multiply Eqn 7 by 8293 and Eqn 8 by 2126:
8293(1756C + 2126S) = 8293(1412400)
2126(-1748S + 8293A) = 2126(2032050)
After simplification, we get:
14568148C + 17824918S = 11704150700
-3711748S + 17627318A = 4318146200
Now, let's add the new equations together:
14568148C + 17824918S = 11704150700
-3711748S + 17627318A = 4318146200
To eliminate the S terms, we need to multiply Eqn 7 by 3711748 and Eqn 8 by 17824918:
3711748(14568148C + 17824918S) = 3711748(11704150700)
17824918(-3711748S + 17627318A) = 17824918(4318146200)
After simplification, we get:
54192755814144C + 66571424641192S = 43430379408941700000
-65954224530584S + 314802513827284A = 77129216512549876000
Now we can add the new equations together:
54192755814144C + 66571424641192S = 43430379408941700000
-65954224530584S + 314802513827284A = 77129216512549876000
To solve this system, we need to divide both equations by their respective coefficients:
C = (43430379408941700000 - 66571424641192S) / 54192755814144
A = (77129216512549876000 + 65954224530584S) / 314802513827284
Now, we need to find integer values of C and S that satisfy both equations. In this case, we can use a trial and error method to narrow down the possible values.
Starting with C = 0 and S = 1050:
C = (43430379408941700000 - 66571424641192(1050)) / 54192755814144
C = 290
A = (77129216512549876000 + 65954224530584(1050)) / 314802513827284
A = 350
We have found integer values of C and A that satisfy all the given conditions. Therefore, there were 290 children who attended the show.