Question 517775
r*t=d
r*t=170
(r+9)*(t-.5)=170
r=51
r+9=60
60*(t-.5)=170
60t-30=170
60t=200
divide by 20
3t=10
t=10/3=3 hrs 20 minutes
or 
51t=170
t=170/51=3.333