Question 884616
Main goal is to find the average speed of travel and the distance from San Diego to Salt Lake City.

r = average speed
d = trip distance between the cities.


First Part:
{{{r*4=d-507}}}


Second Part:
{{{r*8=d-267}}}


Last Part:
We do not yet know but we can find what we need after we solve for r and d.


SYSTEM OF EQUATIONS
{{{highlight_green(4r-d=-507)}}} and {{{highlight_green(8r-d=-267)}}}.
Elimination Method to Eliminate d.
-
{{{8r-d-(4r-d)=-267-(-507)}}}
{{{4r+0=507-267}}}
{{{highlight(r=60)}}}.
-
Either equation to find d,
{{{d=8r+267}}}
{{{d=8*60+267}}}
{{{d=480+267}}}
{{{highlight(d=747)}}}


Using what was found in solving for r and d, the four questions are simpler to answer.