Algebra..please check my work!!
posted by Tim .
At 3 p.m., Brunhilde headed north at 30 kilometers per hour. Two hours later Ludwig headed south at 40 kilometers per hour. At what time will they be 340 kilometers apart?
I know that the distance from Brunhilde(Db) plus the distance from Ludwig(Dl) is equal to 340, which is translated as (Tb)(Rb)+(Tl)(Rl)=340, "T" standing for time, and "R" standing for rate...so I substitue in the rates to get 40Tb + 30Tl=340, but the answer is wrong..the book has it as 9 p.m....what am I doing wrong!!!!?

They separate at a rate of 30 + 40 =
70 km/hr, since they are going in opposite directions. It takes 340/70 = 4.857 hours to become 340 km apart. That would be at 8:51 PM, since 0.857 x 60 = 51+ minutes. Are you sure they didn't ask for the time when they are 350 km apart, not 340? Then the answer would be exactly 9 PM 
Yea the answer in the back of the book has it at 9 p.m. ,and yea they do ask for the time when their 340 kilometers apart, interesting, could the book be wrong?lol

When you divided 340/70 and came up with 4.857, how'd you come up with 8?

The book is correct.
Let the time passed after Ludwig left be t hours, remember he left 2hours after her, so she already went 60 km
So the distance that Brunhilde went is 60+30t
and the distance that Ludwig went is 40t
so....
60 + 30t + 40t = 340
70t = 280
t = 4
So they are 340 km apart 4 hours after Ludwig left, but he left at 5 pm, so they are apart 340 km at 9 pm 
Sorry; I misread the problem and neglected the time delay
Respond to this Question
Similar Questions

math
two horses gallop off in the sam direction. Trigger travels25 kilometers per hour. Silver travels 30 kilometers per hour. How long before the horses are 3 kilometers apart? 
math
Andrea made a car trip of 440 Kilometers. She averaged 54 Kilometers per hour for the frst part of the trip and 80 kilometers per hour for the secound part. If the total trip took 6 hours, how long was she traveling at 80 kilometers … 
MATH
Andrea made a car trip of 440 Kilometers. She averaged 54 Kilometers per hour for the frst part of the trip and 80 kilometers per hour for the secound part. If the total trip took 6 hours, how long was she traveling at 80 kilometers … 
calculus
At noon, you and I start at the same place, and then you head east at a speed of 5 kilometers per hour, and I head north at a speed of 4 kilometers per hour. After two hours, how fast are we moving apart, in kilometers per hour? 
Math
Two airplanes leave St. Louis at the same time and fly in opposite directions. If one travels at 500 kilometers per hour, and the other at 600 kilometers per hour, how long will it take for them to be 1925 kilometers apart? 
Math
Two airplanes leave St. Louis at the same time and fly in opposite directions. If one travels at 500 kilometers per hour, and the other at 600 kilometers per hour, how long will it take for them to be 1925 kilometers apart? 
physics
Canadian snowbirds usually follow the I15 at a speed of about 120 kilometers per hour. Canadian geese, on the other hand, migrate approximately along a northsouth direction for well over a thousand kilometers in some cases, traveling … 
physics
Canadian snowbirds usually follow the I15 at a speed of about 120 kilometers per hour. Canadian geese, on the other hand, migrate approximately along a northsouth direction for well over a thousand kilometers in some cases, traveling … 
physics
Canadian snowbirds usually follow the I15 at a speed of about 120 kilometers per hour. Canadian geese, on the other hand, migrate approximately along a northsouth direction for well over a thousand kilometers in some cases, traveling … 
physics
Canadian snowbirds usually follow the I15 at a speed of about 120 kilometers per hour. Canadian geese, on the other hand, migrate approximately along a northsouth direction for well over a thousand kilometers in some cases, traveling …