A faster train takes one hour less than a slower train for a journey of 200 km. If the speed of the slower train is 10 kmph less than that of the faster train, find the speeds of two trains.
Let the speed of faster train be x km/h.
Then, the speed of slower train is (x − 10) km/h.
Given:
A faster train takes one hour less than a slower train for a journey of 200 km.
$\frac{\text { Distance }}{\text { Speed }}=$ Time
Time taken by faster train to cover $200 \mathrm{~km}=\frac{200}{x} \mathrm{~h}$
Time taken by slower train to cover $200 \mathrm{~km}=\frac{200}{x-10} \mathrm{~h}$
According to the question,
$\frac{200}{x-10}-\frac{200}{x}=1$
$\Rightarrow \frac{200(x)-200(x-10)}{(x)(x-10)}=1$
$\Rightarrow \frac{200 x-200 x+2000}{x^{2}-10 x}=1$
$\Rightarrow 2000=x^{2}-10 x$
$\Rightarrow x^{2}-10 x-2000=0$
$\Rightarrow x^{2}-50 x+40 x-2000=0$
$\Rightarrow x(x-50)+40(x-50)=0$
$\Rightarrow(x-50)(x+40)=0$
$\Rightarrow x=50,-40$
But $(x)$ is the speed of the train, which is always positive.
Thus, $x=50$
and $x-10=40$
Hence, the speed of fast train is 50 km/h and the speed of slow train is 40 km/h.
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