Question 340733
need to know that distance=speed * time;  d=s*t
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walker and biker start at the same time and walk toward each other, so they meet somewhere between at time t
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the distance travelled by walker (d=s*t):  {{{d[w]=3*t}}}
the distance travelled by biker {{{d[b]=12*t}}}
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total distance they both travel =5 miles
therefore {{{d[w]+d[b]=5}}}
{{{(3*t)+(12*t)=5}}}
{{{15t=5}}}
{{{t=5/15=1/3}}}
{{{highlight_red(t=(1/3) hour)}}}