Answer:
Children = 122
Students = 74
Adults = 61
Explanation:
Given
Seating capacity = 257
Charges: Children = $5.00; Students = $7.00; Adults = $12.00
Total sales of ticket = $1860
Required:
Number of children, students and adults present in the theatre.
Let A, C and S represent adult, children and student respectively.
There are half as many adults as there are children; this means that
A = ½C
If the total seat capacity is 257, then
A + C + S = 257
Also, if the total sales of tickets is $1860, then
12A + 7S + 5C = 1860
So, we have two equations to be solved simultaneously.
A + C + S = 257 --- (1)
12A + 7S + 5C = 1860 --- (2)
Substitute ½C for A in (1) and (2)
½C + C + S = 257
Multiply both sides by 2
2(½C + C + S) = 2 * 257
C + 2C + 2S = 514
3C + 2S = 514 ----- (3)
12(½C) + 7S + 5C = 1860
6C + 7S + 5C ,= 1860
6C + 5C + 7S = 1860
11C + 7S = 1860 --- (4)
Make S the subject of formula in (3)
2S = 514 - 3C
S = ½(514 - 3C)
S = 257 - 1.5C
Substituton 257 - 1.5C for S in (4)
11C + 7(257- 1.5C) = 1860
11C + 1799 - 10.5C = 1860
Collect like terms
11C - 10.5C = 1860 - 1799
0.5C = 61
Multiply both sides by 2
2 * 0.5C = 2 * 61
C = 122
Recall that
S = 257 - 1.5C
S = 257 - 1.5(122)
S = 257 - 183
S = 74
Also recall that
A = ½C
A = ½ * 122
A = 61
Hence the attendance at the mobie theatre are;
Children = 122
Students = 74
Adults = 61