Question

places A and B are 100 KM apart on a highway one car starts from A and another from B at the same time if the car travel in the same direction at different speeds they made in 5 hours if they travel towards each other they meet in one hour what are the speeds of the cars
solve using cross multiplication method.​

Answer 1

Answer:

Let,

Case I : Speed of car at A=x

. Speed of car at B=y

Distance of car at A= 5x

Distance of car at B= 5y

5x-5y=100

5(x-y)=100

x-y = 20

x-y-20=0 –––(1)

Case II : Distance of car at A=x

Distance of car at B=y

Speed of car at A=x/1=x

Speed of car at B=y/1=y

x + y = 100

x+y-100=0 –––(2)

Now, by cross multiplication method

x/(-1×-100)-(1×-20) = -y/(1×-100)-(1×-20) = 1/(1×1)-(1×-1)

x/ 100+20 = -y/-100+20 = 1/1+1

x/120 = -y/-80 = 1/2

x/120 = y/80 = 1/2

x/120 = 1/2. and. y/80 = 1/2

x =120/2. and y = 80/2

x= 60. and y = 40

Therefore, Speed of car at A = x = 60 km/h

Speed of car at B = y = 40 km/h