Question 1078524
Not nice that he'd leave her alone, but Jack was always kind of a jerk.
Rate*Time=Distance
{{{R[1]*t=D[1]}}}
{{{R[2]*t=D[2]}}}
{{{D[2]-D[1]=R[2]*t-R[1]*t}}}
{{{D[2]-D[1]=(R[2]-R[1])t}}}
Substituting,
{{{D[2]-D[1]=(15-9)3}}}
{{{D[2]-D[1]=6*3}}}
{{{D[2]-D[1]=18}}}
18 miles apart.