Hello!
When 1/4 is referred as time, it is 1/4 of 60.
1/4 of 60 would be 15 minutes
1/4 hour=15 min
2/4 hour=30 min
3/4 hour=45 min
4/4 hour=60 min
Now what you need to do is multiply 4 w/ 60 to get 240. You now need to add 15 to 240 to get...
255 minutes
I hope this helps!