Question 489635
By himself, Tim can complete his paper route in 160 minutes, With the help of Sue it take 100 minutes.  How many minutes would it take Sue to do the route by herself?
Let x = time (minutes) it takes Sue by herself
then
"time taken by both" times ["rate of Tim" + "rate of Sue"] = "one job"
100(1/160 + 1/x) = 1
multiplying both sides by 160x:
100(x + 160) = 160x
100x + 16000 = 160x
16000 = 60x
266.67 minutes = x