this is about second year homework...?

Question

the metro rail travels 240 at a uniform rate. if the speed have been 8 km per hour more, the journey would have taken 1 hour less.what is the speed of the train?
(pls show solution/representation)

Answer 1

The time to make the 240km is t

so the speed v = 240/t or 240=vt

In the second case the time would be t-1 and you have

v+8 = 240/(t-1) or 240 = (v+8) (t-1)= vt+8t-v-8

so 8t -v -8 =0
8t-240/t -8 =0 , dividing by 8 and multiplying by t
t^2-t-30 =0 you have two answers one is negative, so we neglect

you find t = 5 hours and the speed is 240/5 =48 km/hour

Answer 2

240/x - 1 = 240/(x + 8)
240(x + 8) - x^2 - 8x = 240x
1920 - x^2 - 8x = 0
x^2 + 8x - 1920 = 0
(x - 40)(x + 48) = 0
x = 40 kph

240/40 - 1 = 240/48
6 - 1 = 5

Answer 3

s=240km
s=vt,
240=vt (1)
from the condition of the problem,
(v+8)(t-1)=240
vt+8t-v-8=240
vt+8t-v=248 (2)
(1)->(2)
240+8t-v=248
8t-v=8
v=8t-8

so (8t-8)*t=240
(t-1)t=30
t^2-t-30=0
(t-6)(t+5)=0
t=6, -5
t is positive ,so t=6 and v=240/6=40

solution 40km/h

so