Question 327602
Something is wrong with your problem setup.
If all 300 tickets were Adults, the total receipts would have been $3,000.
If all 300 tickets were Children, the total receipts would have been $1,800.
So the total receipts must range between $1,800 and $3,000.
A total of $1,200 is not possible and leads to a solution of 450 Childrens tickets and -150 Adult tickets, which is a nonsensical solution.
Please check your problem setup and repost.