Make the fraction a decimal.
3÷5= 0.6
Now add the whole number and that makes it 2.6
That's how long he travels in one minute. There are 60 minutes in an hour so multiply it by 60 and see if that gets you close to 350.
60x2.6= 156
Now let's add one more hour.
156+156= 312
That's pretty close to what we want. Now, keep adding minute at a fast rate to get where you need to be.
14x2.6=36.4
312+36.4= 348.4
348.4+2.6=351
So two hours and fourteen minutes