Question 337431

Rate*Time=Distance
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{{{R1*T1=D}}}
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{{{R2*T2=D}}}
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{{{R2=30+R1}}}
{{{R1=R2-30}}}
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{{{T1=D/R1}}}
{{{T2=D/R2}}}
{{{T=T1+T2=D/R1+D/R2=D/(R2-30)+D/R2=D(1/(R2-30)+1/R2)}}}
{{{R2=X}}}
{{{highlight(T=D(1/(X-30)+1/X))}}}