Question

a man travels from home to town back in a motorcycle travel to home from town at a speed which 20 kilometre per hour more than a journey to the town from home the average speed of his total journey was 48 kilometre ​

Answer 1

Therefore the man travel to home from town at 60 km/h

Explanation:

Let the distance between home and town be x.

and speed =y when he travels to home from town

and speed = y-20 when he travels to the town from home.

Time= distance / speed

Therefore total time =$\frac{x}{y} +\frac{x}{y-20}$ = $\frac{x(2y-20)}{y(y-20)}$

Average speed =$\frac{2x}{\frac{x(2y-20)}{y(y-20)}}$  $=\frac{2y(y-20)}{2(y-10)}$

according to the problem

$\frac{2y(y-20)}{2(y-10)}=48$

$\Leftrightarrow y^2 -20y=48y-480$

$\Leftrightarrow y^2-68y+480=0$

Therefore y = 60 and 8

We are taking y=60 since average speed 40 k/h.

Therefore the man travel to home from town at 60 km/h