Time taken by Nathaniel for wielding a railing = 75 minutes
Time taken by Brenda for wielding the same railing = 75 - 25 minutes
= 50 minutes
Time taken by both of them together
to wield the railing = (75 * 50)/(75 + 50)
= 3750/125
= 30 minutes
I hope the procedure is clear enough for you to understand.
