Question 490963
By himself, Tim can complete his paper route in 160 minutes. With the help of Sue it takes 100 minutes. 
How many minutes would it take Sue to do the route
:
Let s = S's time to do the job alone
let the completed job = 1 (all papers delivered)
:
Each will do a fraction of the job. the two fractions add up to 1
:
{{{100/160}}} + {{{100/s}}} = 1
multiply by 160s, results
100s + 160(100) = 160s
16000 = 160s - 100s
16000 = 60s
s = {{{16000/60}}}
s = 266{{{2/3}}} min for S to do it alone
:
:
Check this
100/160 + 100/266.67 = 
.625 + .375 = 1