Question 1149021
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Let x be the rate of the boat; then the rate of the car is 5x.

And let "d" be the traveled distance.


The time spent on the car was  {{{t[car]}}} = {{{((4/5)*d)/(5x)}}}  hours.


The time spent on the boat was  {{{t[boat]}}} = {{{((1/5)*d)/x}}}.


The ratio  {{{t[car]/t[boat]}}} = {{{((4/5)*d)/(5x)}}} : {{{((1/5)*d)/x}}} = {{{4/5}}}.


Thus we need to separate 12 hours in two parts in proportion {{{4/5}}}.


So, the parts are  {{{12*(4/9)}}} = {{{48/9}}} = {{{5}}}{{{1/3}}} hours for the car and  12 - {{{5}}}{{{1/3}}} = {{{6}}}{{{2/3}}}  hours for the boat.
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Solved.