Ba xe ô tô đi một lúc a để đến b , vận tốc ôtô đầu tiên là 30 km/giờ , vận tốc ôtô thứ 2 là 45 km /giờ . Ôtô đền b sớm ô tô đầu tiên ba mươi phút và chậm hơn ô tô thứ 2 bốn mươi p...

To solve this problem, we can use the formula: $$ Let's denote: - $$ as the time taken by the first car to reach point b - $$ as the time taken by the second car to reach point b We have the following information: - Speed of the first car, $$ - Speed of the second car, $$ - The second car arrives 30 minutes earlier than the first car, so $$ - The second car is 40 minutes slower than the first car, so $$ Firstly, we need to find $$ and $$. We can set up a system of equations using the given information: $$ $$ Solving these equations will give us values for $$ and $$. Once we have found $$ and $$, we can calculate the distance between points a and b using either of these times. Let's use $$ for this calculation. The distance between points a and b is given by: $$ Substitute in the known values to find $$. Finally, to find the speed of the third car ($$), we can use: $$ Where, $$ is calculated as follows: $$ Substitute in the known values to find $$. By solving these equations step by step, you will get: $$ $$