$16 per adult, $10 per child, Total of $502
The number adults multiplied by the cost for adult plus the number of children multiplied by the cost for children is 502:
First answer:
16A + 10C = 502
If C = 39:
16A + 10(39) = 502
16A = 502 - 10(39) = 502 - 390 = 112
16A = 112
A = 112/16 = 7
A= 7
Second answer:
7 adults