A passenger train takes 3 hours less for a journey of 360 km if its speed is increased by 20km/hr from its usual speed. We need to find its usual speed. Represent the problem situation in the form of a quadratic equation.

Explanation

Let usual speed of train is `x` km/h.

Let the time taken by the train to cover `360` km distance with normal speed is `t` hour.

Then, `360/x = t->(1)`

When speed is increased by `20` km/h, then,

`360/(x+20) = t-3->(2)`

Subtracting (1) from (2),

`360/(x+20) - 360/x = -3`

`=>360x -360x-7200 = -3x(x+20)`

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