Person A chases person B. As measured in the ground frame, they have speeds 4c/5 and 3c/5,

Question:

Person A chases person B. As measured in the ground frame, they have speeds 4c/5 and 3c/5, respectively. If they start a distance L apart (as measured in the ground frame), how much time will it take (as measured in the ground frame) for A to catch B?