Let’s consider the car starting from point A as X and its speed as x km/hr. 

And, the car starting from point B as Y and its speed as y km/hr. 

It’s seen that there are two cases in the question: 

# Case 1: Car X and Y are moving in the same direction 

# Case 2: Car X and Y are moving in the opposite direction 

Let’s assume that the meeting point in case 1 as P and in case 2 as Q. 

Now, solving for case 1: 

The distance travelled by car X = AP 

And, the distance travelled by car Y = BP

As the time taken for both the cars to meet is 7 hours, 

The distance travelled by car X in 7 hours = 7x km [∵ distance = speed x time] 

⇒ AP = 7x 

Similarly, 

The distance travelled by car Y in 7 hours = 7y km 

⇒ BP = 7Y 

As the cars are moving in the same direction (i.e. away from each other), we can write 

AP – BP = AB 

So, 7x – 7y = 70 

x – y = 10 ………………………. (i) [after taking 7 common out] 

Now, solving for case 2: 

In this case as it’s clearly seen that, 

The distance travelled by car X = AQ

And, 

The distance travelled by car Y = BQ 

As the time taken for both the cars to meet is 1 hour, 

The distance travelled by car x in 1 hour = 1 x km 

⇒ AQ = 1x 

Similarly, 

The distance travelled by car y in 1 hour = 1y km 

⇒ BQ = 1y 

Now, since the cars are moving in the opposite direction (i.e. towards each other), we can write 

AQ + BQ = AB 

⇒ x + y = 70 …………… (ii) 

Hence, by solving (i) and (ii) we get the required solution 

From (i), we have x = 10 + y……. (iii) 

Substituting this value of x in (ii). 

⇒ (10 + y) + y = 70 

⇒ y = 30 

Now, using y = 30 in (iii), we get 

⇒ x = 40 

Therefore, 

– Speed of car X = 40km/hr. 

– Speed of car Y = 30 km/hr.