can anyone help me w/ this math word problem?

Question

the ride in was quick, as the speed was 400 kilometers per hour. the ride out at 100 kilometers per hour was much more relaxing. if the total time in and out was 40 hours, what was the distance in?

Answer 1

Can we assume that the distance out was the same as the distance back in? Call it "D".

Then use Time = distance divided by speed.
T = 40 = D/100 + D/400 = 0.0100 D + 0.0025D = 0.0125D
So we have 40 = 0.0125 D
Divide both sides by 0.0125
40 / 0.0125 = 0.0125 D / 0.0125 = D

Answer 2

if the two digit huge variety is 10x + y then x + y = 13 and 10y + x = 10x + y + 40 5 giving 9x + 9y = 117 and 9y -- 9x = 40 5 including the two we get 18y = 162 => y = 9 giving x = 13 --y = 13 --9 = 4 so the two digit huge variety is 10x + y = 10*4 + 9 = 40 9 be certain : 4 + 9 = 13 and ninety 4 = 40 9 + 40 5

Answer 3

Sure. You rode for 40 hours, but 4/5 of that was spent on your leisurely departure. So in cost 8 hours, and out took 32. That will be 3200km, obviously the same in both directions. Quite a commute, even for an American.

Answer 4

16 hours set up a proportion 400/100 y/40 (you would want to set them up up and down it's easier to undestand that way) then cross multiple 400 x 40=1600 anddivide it by 100=16 hours

Answer 5

6400 km..

Let's let x be the distance in one direction:

x/100 + x/400 = 40 hours
4x/400 + x/400 = 40
5x/400 = 40
5x/400 * 400 = 40 * 400
5x = 16000
5x/5 = 16000/5
x = 3200

Since round trip is 2x, the total distance would be 6400 km


Hope this helps!

Answer 6

400km +100km = 500km
40hours/5 = 8
8x400=3200 in
32x100=3200 out (just to verify)
3200 KM is the answer