Question 178777
Let x=time it takes to walk 8 mi or jog 12 mi

distance=rate*time
rate=distance/time

Therefore,
{{{8/x}}}=his walking speed
{{{12/x}}}=jogging speed

His jogging rate is 5 miles per hour faster than his walking rate.
So,
{{{12/x=8/x+5}}}
{{{12/x=8/x +5x/x}}}
{{{12/x=(5x+8)/x}}}
x(5x+8)=12x
5x^2+8x=12x
5x^2-4x=0
5x-4=0
x=4/5

walking rate={{{8/x=8/(4/5)=8(5/4)=2*5=10}}}mi per hr

x=4/5=time it takes to walk 8 miles.

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