Solution (By Examveda Team)
$$\eqalign{
& {\text{According to question,}} \cr
& \,\,\,\left[ {4 - \frac{5}{{1 + \frac{1}{{3 + \frac{1}{{2 + \frac{1}{4}}}}}}}} \right] \cr
& = 4 - \frac{5}{{1 + \frac{1}{{3 + \frac{1}{{\frac{9}{4}}}}}}} \cr
& = 4 - \frac{5}{{1 + \frac{1}{{3 + \frac{4}{9}}}}} \cr
& = 4 - \frac{5}{{1 + \frac{1}{{\frac{{31}}{9}}}}} \cr
& = 4 - \frac{5}{{1 + \frac{9}{{31}}}} \cr
& = 4 - \frac{5}{{\frac{{40}}{{31}}}} \cr
& = 4 - \frac{{5 \times 31}}{{40}} \cr
& = 4 - \frac{{31}}{8} \cr
& = \frac{1}{8} \cr
& {\text{According to question}} \cr
& \frac{1}{8}{\text{part = 10 minutes}} \cr
& {\text{1 part = 10 minutes}} \cr
& \frac{3}{5}{\text{ part = 80}} \times \frac{3}{5} \cr
& {\text{ = 48 minutes}} \cr} $$
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