Question

The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 Kms. in 5
hours, the speed of the first train is
(a) 10 Km/hr (b) 50 Km/hr (c) 70 Km/hr (d) none of these​

Answer 1

the second train runs 400 Kms. in 5 hours
the second train runs 80 Kms. in 1 hours,
let the speed of first one is x km / hr
According to Question
$\frac{7}{8} = \frac{x}{80} \\ \frac{7 \times 80}{8} = x \\ 70 = x$
so option c is the correct answer .

Answer 2

hope it helps.............