Answer: He trained for 98 days for a marathon.
Step-by-step explanation:
Since we have given that
Number of weeks Marcus ran to train for a marathon = 14
As we know that
[tex]1\text{ week }= 7\text {days}\\\\14\text{ weeks }=7\times 14\text{ days }=98\text{ days}[/tex]
So, he trained for 98 days for a marathon.