Question

A and B started travelling towards each other at the same time, from places X to Y and Y to X, respectively. After crossing each other. A and B took 2.45 hours and 4.05 hours to reach Y and X, respectively. If the speed of B was 8.4 km/h, then what was the speed (in km/h) of A?​

Answer 1

3:5

Step-by-step explanation:

Let say Distance between A & B  is  D km

Speed of Train starting from A  = A km/Hr

Speed of Train Starting from B  = B km/Hr

Let say after T hr they crossed each other

=>  AT + BT  =  D     - eq 1

=> T = D/(A+B)

A ( T + 25)  = D  => AT  + 25A  = D     - eq2

B ( T + 9) = D  => BT + 9B = D     - eq 3

Eq 2 + eq3 - eq 1

=> 25A + 9B = D

=> 25A + 9B = AT + BT  - eq 4

Eq 2 - E3

AT - BT + 25A - 9B = 0

=> 25A - 9B = BT - AT    - eq 5

Adding eq 4 & eq 5

50A = 2BT

=> 25A = BT   - eq 6

Eq 4 - Eq 5

18B = 2AT    

=> 9B = AT    - eq 7

eq6/eq7

25A/9B = BT/AT

=> 25A/9B = B/A

=> 25A² = 9B²

=> A²/B² = 9/25

=> A/B = 3/5

A: B :: 3: 5