We need to use the following formula of distance .
Distance= speed * time .
For the first time
distance = 6r
And let the average rate for the second time be s
So distance = 5s
Since distance remains same, so we get
6r=5s
Now we have to solve for s. And for that we need to get rid of 5, by dividing both sides by 5, that is
[tex] s =\frac{6r}{5} [/tex]
And that's the required average rate for the second trip .