Question 928699
RT=D   using rate miles per hour.


r for the jackel's speed;
The elk's speed is r+10;
The cheetah's speed is 2r.


Everybody is moving for 1 hour.  Sum of their distances ,   150 miles.
{{{(2r+(r+10)+r)*1=150}}}
{{{4r+10=150}}}
{{{4r=140}}}
{{{r=140/4}}}
{{{highlight(r=35)}}} the JACKEL.


That value means, the cheetah goes 70 mph and elk goes 45 mph.