Question 399920
rate of Tim = 1/80
rate of Sue = 1/s
Then {{{50(1/80 + 1/s) = 1}}}
==> {{{1/80 + 1/s = 1/50}}}
==> {{{1/s = 3/400}}}
==> {{{s = 400/3 = 133&1/3}}} minutes.