Question 1164425
one group travels 1 1/2 mile per hour faster than the other​ group<pre>

Let the SECOND quantity mentioned (i.e., the "other group"'s rate, i.e., the
slower group's rate, be the one to represent by the letter for its unknown
quantity.  

So let r = the slower group's rate

Then use the sentence again to define the FIRST mentioned group's rate in
terms of the second one mentioned in the sentence.

</pre>one group travels 1 1/2 mile per hour faster than the other​ group<pre>

So the first (faster) group's rate is r + 1.5

Their approach rate is the sum of their rates, which is r + r + 1.5 or
2r + 1.5

Then it's just 

DISTANCE =    RATE   x TIME
    |          |     |  | 
  1050   = (2r + 1.5)∙(200)


Solve that for the rate of the slower group, then add 1.5 mi/h to get the
rate of the faster group.

Edwin</pre>