For a dual-isotope clinical scan, a patient is administered a mixture containing two diagnostic radiopharmaceuticals. The administered dose consists of radionuclide XXX with an initial activity of 320 MBq320\text{ MBq}320 MBq and radionuclide YYY with an initial activity of 240 MBq240\text{ MBq}240 MBq.
Radionuclide XXX has a physical half-life of 6 hours6\text{ hours}6 hours, and radionuclide YYY has a physical half-life of 8 hours8\text{ hours}8 hours.
Assuming no biological excretion occurs during this period, what is the total activity of the remaining radionuclides in the patient's body after 24 hours24\text{ hours}24 hours?
20 MBq20\text{ MBq}20 MBq
30 MBq30\text{ MBq}30 MBq
50 MBq50\text{ MBq}50 MBq
70 MBq70\text{ MBq}70 MBq
