Mr. Karthik drives to work at an average speed of 48 km/hr. Time taken to cover the first 60% of the distance is 20 minutes more than the time taken to cover the remaining distance. Then how far is his office ?

Let the total distance be 'x' km.

Time taken to cover remaining 40% of x distance is    $t1=\frac{40\times x}{100\times 48}$

But given time taken to cover first 60% of x distance is    $t2=t1+\frac{20}{60}hrs$

  $t2=\frac{60\times x}{100\times 48}$

$\therefore \frac{60\times x}{100\times 48}= \frac{40\times x}{100\times 48}+\frac{20}{60}$

 x=80 km.