We will have the following:
First, we have that the rates for Morgan and Kendall will be the following (Respectively):
[tex]r_1=v+1[/tex]&
[tex]r_2=v[/tex]And the distance will be given by:
[tex]d=((r_1+1)+(r_2))\cdot t[/tex]Here "t" is the time.
Now, we replace the values and solve for the rate "v":
[tex]21=((v+1)+v)\cdot2\Rightarrow21=(2v+1)\cdot2[/tex][tex]\Rightarrow2v+1=\frac{21}{2}\Rightarrow2v=\frac{19}{2}[/tex][tex]\Rightarrow v=\frac{19}{4}[/tex]So, Morgan and Kendall's rates are respectively:
[tex]M=\frac{23}{4}\cdot\frac{m}{h}[/tex]&
[tex]K=\frac{19}{4}\cdot\frac{m}{h}[/tex]