Question 1066484
.
<pre>
{{{360/u - 360/(u+5)}}} = 1,

360*(u+5) - 360u = u*(u+5),

360u + 1800 - 360u = u^2 + 5u,

u^2 + 5u - 1800 = 0.

(u+45)*(u-40) = 0.

<U>Answer</U>. 40 mph.
</pre>