<p>Why do you need a formula for that? Don’t clog your brain with formulas, use logic. </p>
<p>v1 = d1 / t1
(4) = (7) / t1
t1 = 7 / 4</p>
<p>v2 = d2 / t2
(1) = (7) / t2
t2 = 7</p>
<p>velocity = (delta)position / (delta)t
velocity = (14) / [ (7/4) + 7]
velocity = 14 / (53/4)
velocity = 56 / 53 mi/h</p>