Read the following scenario and answer the question that follows:

Samantha recently completed her law degree and asks her friend, Mary, to lend her R1000 so that she can buy a beautiful dress to wear at her graduation. Mary agrees, on condition that Samantha gives her a sound system as security for the debt. As soon as Samantha repays Mary the R1000, Mary will return the sound system to Samantha.

What is the above arrangement between Samantha and Mary called?