Question 917930
First convert the time from mins to hours 

30mins(1hr/60min) = .5hr

15mins(1hr/60min) = .25hr


D = R1*T1 + R2*T2 in this case

D = 5mi/hr * .5hr  + 6mi/hr * .25hr 
  
  = 2.5mi + 1.5mi = 4mi