Question 1207696
<pre>
Let's pick a ridiculous distance to school, one that halfway is divisible
by both 2 and 7.  Halfway would be 14 miles and the whole distance to school
would be 28 miles.

(Yes, I know that's a long way to walk and run to school! lol). Anyway,

She walks the first 14 miles at 2 mph, which takes her 7 hours.

She runs the remaining 14 miles at 7 mph in 2 hours.

So she travels 28 miles in 9 hours.

So her average speed is 28/9 = 3 1/9 mph.

Edwin</pre>