Let, x b hrs truck drove. so in x hrs, truck covered: 45*x miles since car drove 2 hrs less than x, car covered: 60* (x-2) miles as u mentioned, both covered equal distance: 45*x=60* (x-2) ie, x = 8 hrs x-2 = 6 hrs miles covered = 6*60 or 8*45 = 360 miles

perfectionist · Mar 31, 2011 12:19 PM

Velocity=Distance travelled/ time taken V=D/T Thus, T=D/V Given, V(truck)=45 mph V(car)=60 mph. Assume they both travel D miles of distance. Say, the Truck takes X hours to finish the distance of D miles. Then X = D/45 (Hrs = Miles / Miles/Hr) Also, say the car takes Y hours to travel the same distance D. Then Y= D/60 Then Y (hrs) = D (miles)/ 60 MPH We also know the truck travels 2 hrs longer. Thus X=Y+2 Putting all together, D/45= (D/60)+2 or, (4D-3D)/180 = 2 Thus D=360 miles. Then the truck travelled, X hrs = D/45 = 360/45 = 8 hrs. And the car travelled, Y=D/60 = 360/60=6 hrs.

Stiffler · Mar 31, 2011 12:20 PM

Always calculate interms of D=RxT!

kanchu! · Mar 31, 2011 12:23 PM

After hours of घोत्ल्याइ and your answer give me idea  , Can we do this way? x  for truck and y for car. As per Stiffer , 45x=60y                               x= y+2 45 x   -  60y   =     0       x   -      y   =    2 -------------------------- For American High School children have to be simplest way ( they can not understand certain math). Last edited: 31-Mar-11 01:09 PM

syanjaali · Mar 31, 2011 12:58 PM

While they are in equation form, I thought my answer would be more easier to understand, no? By the way, the second equation is wrong. X=y+2 (truck travels 2 hrs longer). Thus X-Y=2 (not -2)

Stiffler · Mar 31, 2011 1:03 PM

Equation 1 for Truck : TurckDistance = TruckVelocity * TruckTime where Trucktime = (CarTime + 2) Thus TruckDistance = TruckVelocity * (CarTime + 2) Equation 2 for Car: CarDistance = CarVelocity * CarTime Thefore: TruckVelocity * (CarTime + 2) = CarVelocity * CarTime 45 ( CT + 2) =60 * CT 45CT + 90 =60CT 15CT =90 CarTime = 6 Thus 6 hour is the Car's time. Plug in the value of Cartime 6 in the equation 1 for truck to get the Distance travelled which will give you 360 miles. Derive your answer using the equation : Distance = Velocity * Time (As mentioned by Kanchu! )

Nas · Mar 31, 2011 1:04 PM

Thank you all for your input. Student liked the way Stiffer explained, higher grade with math interest student  liked NAS, I thought  I came wth the simplest form , without explanation , just did as I did to pass the EXAM. Thank you agian.

Syanjaali · Apr 1, 2011 3:05 PM