At the end of a factory assembly line, completed widgets are deposited into a box until it is filled. if after 10 minutes the box contains 25 widgets and it takes 2 hours total to fill up a box, how many widgets must each box hold?

In this question we are asked to calculate how many widgets a box can hold.
2 hours - 60 minutes / hour * 2 = 120 minutes 
after 10 minutes - box contains 25 widgets
this means that it takes 10 minutes to fill - 25 widgets
in 1 minute - 25/10 widgets/minute 
therefore within 120 minutes - 25/10 widgets/minute * 120 minutes 
the number of widgets a box can hold  - 300 widgets