John can complete a paper route in 20 minutes.
John's 1 minute work = 1/20 , so rate =1/20 job/minute
Steve can complete the same route in 30 minutes
Steve's 1 minute work =1/30, so rate =1/30 job/minute
Together DATA:
Time = y min/job ; Rate = 1/y job/min
rate + rate = together rate
1/20 + 1/30 = 1/y
(30+20)/600 = 1/y
50/600
5/60 = 1/y
y = 60/5 = 12 minutes (time for this to do the job together)