Question

Explain it so I can better understand it

Answer 1

The question is essentially asking who's equation works better (Part A) and to explain why (Part B). 
Marcella is suggesting the equation 6r + 12 = 683.88 
Julia is suggesting the equation 6(r + 12) = 683.88 

Six people are on the trip.
It is $12 PER person to rent a floatation device. 
The total cost of the trip was $683.88.

Hope I've helped!