Answer:
Mr. Marcum bought 5 child tickets and 2 adult tickets.
Step-by-step explanation:
First, assume that Mr. Marcum bought either 7 tickets of child tickets or 7 tickets of adult tickets. I'm using 7 child tickets for this working.
If Mr. Marcum bought 7 child tickets,
total money spent = $4 * 7 = $28
This is not equal to $40 and there has to be more money spent.
We should also calculate the price difference between the adult ticket and the child ticket.
Price difference per ticket = $10 - $4 = $6
This means that if Mr. Marcum bought an adult instead of a child ticket, he would spend $6 more.
In this case, Mr. Marcum has to spend $40- $28 = $12 more.
Hence, the number of adult tickets replacing the child tickets is $12/$6 = 2.
The number of child tickets = 7 - 2 = 5