The table below shows the ticket rates for whale watching trips offered by Ocean Tours. Age Ticket Price Under three years free Three to 12 years $36 Over 12 years $48 On a certain day, the company took 92 people on whale watching trips. There were 40 children aged 12 and under, of which some children were under three years. If x represents the number of children under three years, which equation can be used to find the value of x, where C represents the total amount of money collected from tickets that day?