Question

If a man travels at a speed of 30 km/hr, he
reaches his destination 10 minutes late and if
he travels at a speed of 42 km/hr, he reaches
his destination 10 minutes early. The distance
travelled is :
​

Answer 1

First of all convert the speed to km/min to make calculation easier. Apply the formula, speed = distance/time for both and make equations.

Let distance be Xkm and time be Ykm.

For first equation,

30/60=X/Y+10

>X=30Y+300/60

For second equation,

42/60 = X/Y-10

>X=42Y-420/60

Now equating both equations, we get,

Y=60min

Now, put value of Y in any of the above equation, you'll get X=35km.

Answer 2

Answer:

Distance travelled is 35km

Step-by-step explanation:

Let the distance be x km

Time at the speed of 30km/h = X/30 - 10 /60 ---------------(1)

Time at the speed of 42km/h  == X/42+10/60 ------------(2)

solving  equations 1 and 2

x/30 -10/60= x/42 +10/60

x/30 -x/42= 10/60+10/60

42x-30x/1260= 20/60

12x/1260=2/6

x= 1260x 2/72

x= 35km

∴The distance  travelled is 35km