Question 856256
Vivek bike problem seems to be the more complicated exercise you have.


Only can guess that Friedell is the school for the destination.
Let r = biking speed


______________speed__________time___________distance
Biking________r______________(___)______________1
Walking______r-3_____________(___)______________2=3-1
Total_________________________1_________________3


Fill in the time expression using RT=D as T=D/R.


______________speed__________time___________distance
Biking________r______________1/r______________1
Walking______r-3_____________(2/(r-3))________2=3-1
Total_________________________1_______________3


Time sum equation uses only one variable, r.
{{{highlight(1/r+2/(r-3)=1)}}}  LCD is {{{r(r-3)}}};
Multiply members by {{{r(r-3)}}};
{{{r-3+2r=r^2-3r}}}
{{{cross(r^2-3r-r+3=0)}}}------MISTAKE HERE.
{{{r^2-3r-2r+3=0}}}-------CORRECTED.
{{{r^2-5r+3=0}}} NOT FACTORABLE.
discriminant=25-4*3=25-12=13
{{{r=(5+- sqrt(13))/2}}}-----but not reasonable to have both values.
{{{r=(5-sqrt(13))/2}}} or {{{highlight(r=(5+sqrt(13)/2))}}}
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The subtraction form will make no sense, because then the walking speed would become negative.
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FINISHED ANSWER:  The plus form must be chosen.  That one is near to 4.3 mph; Riding speed is 4.3 mph and walking speed is 1.3 mph.