Question 1015510
RT=D relates rate, time, distance.  Study this table of data, and decide how to supply the missing
information.
<pre>
                     rate         time     distance
secondary roads       r            5
interstate hwy        r+15         3
Total                                        445
</pre>

This is how to do that:
<pre>
                     rate         time     distance
secondary roads       r            5       r*5
interstate hwy        r+15         3       (r+15)*3
Total                                        445
</pre>

Distance sum is the equation in one variable only, r,
{{{highlight(5r+3(r+15)=445)}}}.