First define the variables:
c = amount of children
a = amount of adults
Next create the equations to satisfy the conditions:
1) Total group is 12 people:

2) Total cost is $100 with adults costing $10 and children being $6:

Answer:
here are 4 different types of prisms
Step-by-step explanation:
2 rooms would be 62+42 which is 104
3 rooms would be 104+42 which is 146
4 rooms would be 146+42 which is 188
5 rooms would be 188+42 which is 230
6 rooms would be 230+42 which is 272
but these are the prices including the 20$
without the 20$ the prices would be
2 rooms is 84
3 rooms is 126
4 rooms is 168
5 rooms is 210
6 rooms is 252