=60/(3/4)

=80 km/h

Time required to drive 1 km.

=(3/4)/60

=3/240

= 1/80 (hours)

===============

4/5 divided by 3/ 10 equals 8/3 km/h.

You can walk 8/3Km less than 3Km in an hour.

So you can't walk 3 kilometers.

If my answer is correct, please give me a high score. Ha ha laugh