speed of car : speed of train $:100:150=2:3$
$\Rightarrow$ time needed for car : time needed for train $=3:2$
$\Rightarrow$ i.e., the train only takes $\frac{2}{3}$ of the time taken by car.

Since both the car and train start and reach at the same time,
$\frac{1}{3}$ of the time needed by car is $12.5$ minutes.
$\Rightarrow$ Time needed by the car $=3\times 12.5\text{min}$

(Or)