Answers

2016-07-17T16:57:33+08:00
            rate x  time = distance; 
 
time(truck)-time(car)=2; or t(car)=t(trck)-2
         
          rate     x  time=distance
car = (20 + r )  (t-2)  = 350
truck= (r)          (t)    =350

20t +rt -40-2r=350....1.);
              rt = 350.......2.)
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20t +350-40-2(350/t)=350;
20t^2-40t-700=0;
t^2-2t-35=0;
(t -7)(t+5)=0;
t=7;
 time (car)=7-2;
                =5 hrs
rate of car = 350/5
                 =70 kph...........ans
rate of truck=350/7;
                  =50kph.............ans


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