Question 616060
Okay, so if they walk toward each other and it takes 1 hour then their cumulative speed must be 4.4 miles per hour (mph). Let us say that Rob's speed is r and Juan's speed is j.

So r + j = 4.4 mph

Now as Rob catches up with Juan he must start from behind and is walking faster than Juan, but how much faster?

Well, over 11 hours he walks an extra 4.4 miles.

So his speed compared to Juan's is 4.4 miles divided by 11 hours faster

= 4.4/11
= 0.4 mph faster than Juan

so as Juan's speed is j then Rob's speed is j + 0.4

Now we said that Rob's speed is r. If we write it using the above formula:

r = j + 0.4

Now if look at the first equation r + j = 4.4 

We can replace the r with (j + 0.4) as so:

(j + 0.4) + j = 4.4

j + 0.4 + j = 4.4

and solve for j: ( we move the 0.4 to the right side. When we change the side of a number we have to change it's sign (in this case from positive to negative). We also add the j's together.   :

2j = 4.4 - 0.4

2j = 4.0

j = 2.0

So Juan walks at 2 mph

We know that Rob walks 0.4 mph faster than Juan so Rob walks at 

2.0 + 0.4 = 2.4 mph !!!