Answer:
The answer to your question is:
adult = £ 11
children = £ 8.5
Explanation:
Data
Smiths 3 adults 4 children £67
Jones 5 adults 6 children £ 106
adult = a
child = c
Process
3a + 4c = 67 (1)
5a + 6c = 106 (2)
Solve the equations using the elimination method
Multiply (1) by -5 -15a - 20c = -335
Multiply (2) by 3 15a + 18c = 318
0 - 2c = -17
c = 17/2
c = £ 8.5
Solve (1) for a 3a + 4(17/2) = 67
3a + 34 = 67
3a = 67 - 34
3a = 33
a = 33/3
a = £11