#### Answer

$-r = t-s$

#### Work Step by Step

We use the equation for slope:
$m = \frac{y_2-y_1}{x_2-x_1}$
We set the two slopes equal to each other, for they are parallel:
$ \frac{v}{-r} = \frac{v}{t-s} \\ \frac{1}{-r} = \frac{1}{t-s} \\ -r = t-s$

Published by
Brooks Cole

ISBN 10:
9781285195698

ISBN 13:
978-1-28519-569-8

$-r = t-s$

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