Question 1052252
RT=D Constant Travel Rate Rule

<pre>
                  SPEED           TIME          DISTANCE
WITHWIND          r+15             t             420
AGAINSTWND        r-15             t             350
</pre>

Remind yourself what the description said about the time quantities, and notice both are assigned as t.




continuing from the table,


{{{420/(r+15)=350/(r-15)}}}


{{{6/(r+15)=5/(r-15)}}}


{{{6(r-15)=5(r+15)}}}


{{{6r-6*15=5r+5*15}}}


{{{r=5*15+6*15}}}


{{{r=11*15}}}


{{{highlight(r=161)}}}--------speed of plane in still air.