Question 1156291
You want to show your function as  r(x) = (30 + x)/(3/4+x/85).

<pre>
PART      SPEED       TIME        DISTANCE

first       40         30/40        30

last       85          x/85         x

TOTALS              x/85+3/4      x+30
</pre>
function for average rate r for whole trip:

{{{r(x)=(x+30)/(x/85+3/4)}}}


With algebra steps, rewritten as {{{r(x)=(340x+10200)/(4x+255)}}}


To answer the question "a",  let r(x) equal 60, and solve the equation for x.