Bill put his french fries in the oven after it finished heating.  The recommended time was 5 minutes for them to be fully cooked.  He put them in for 45 seconds.  How many seconds remained?
Each minute last 60 seconds, so that means for the fries to be fully cooked Bill needs to cook them for 5*60=<<5*60=300>>300 seconds
Since Bill had the fries in the oven for 45 seconds so far, that means they need to stay in the oven for another 300-45= <<300-45=255>>255 seconds.
#### 255