The answer is 160 children’s tickets were sold that day
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:

Interior angles of a triangle should always add up to 180.
180-154=26
26-13=13
X=13