Question 47060
D=R*T DISTANCE = RATE * TIME OR T=D/R & SEEING AS THE TIMES ARE THE SAME WE SET EACH TRIP EQUAL THUS 20/(x+9)=15/x or 20x=15x+135 or 5x=135 or x=135/5 or x=27 or x+9=36 for the speed on the side roads.
ANS. IS B)36 MPH