Since the question requires you to give the answer in terms of steps/minute, the first step would be to convert hours to minutes:
12.5 hours = 750 minutes
Next, if he took 775 steps in 750 minutes, how many would he take in 1 minute?
This requires you to set up the question as a proportion:
(775 steps/ 750 minutes) = (x steps/1 minute)
(1 * 775)/750 = 31/30 = 1.033
he took ~1 step per minute
