Question 344533
Rate*Time=Distance
{{{R*t=D}}}
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.
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During the {{{1}}} hour difference, Car A moved {{{20}}} miles away from point O.
Car A's distance from point O would be,
{{{D[a]=20t+20}}}
Car B's distance would be,
{{{D[b]=50t}}}
The distance between them, {{{D}}}, would be 
{{{D=D[a]-D[b]}}}
{{{D=20t+20-50t}}}
{{{highlight(D=-30t+20)}}}