Judah collects toy cars. he buys his cars in packs of 12,18 and 24.he wants to arrange them in rows but all the rows have to be an equal amount of cars. what is the total amount of cars in rows that he can arrange his cars in

For this case what we can do first is to take an average of the number of cars.
 We have then:
 P = (12 + 18 + 24) / (3)
 P = 18
 In other words, you can organize your cars in rows of 3 where each row will have 18 cars.
 
 three rows, 18 cars per row.