Well, this may be simpler than you think. Break down the problem first. 10 is half of 20, right? Here is your problem solved in numbers:
10 hrs x2 = 20 hrs
210 bagels x2 = 420 bagels
All you had to do was multiply the original number by 2 since you had to find the number in 20 hours and you already had the number for 10. What you do to the top of the fraction, you must do to the top. So, there are 420 bagels in 20 hours.
Next, you must find the unit rate. To do this, you have to divide the top and bottom of the fraction by the greatest common factor. The top of the fraction is 10, and 10 can go into 210, so that must be our GCF (greatest common factor). 210 divided by 10 is 21 (just take the 0 off the end!) Then, 10 divided by 10 is 1. So, your unit rate is 21 bagels per hour.
Thanks for the opportunity to answer your question and I hope this helped! :)
Please ask if you need more information! :)
