Hi,
The answer is 1219/3000000 Km/Hr
How I got my answer:
Convert yard to foot
3 foot=1 yard
2/3*3=2 foot
Now convert foot to km
1 foot=0.0003047 km
2 foot= 0.0003047*2
2 foot= 0.0006095 km
speed(yards can the snail crawl in 1 hour)=distance/time
speed=0.0006095/1.5 Km/Hr
speed=0.006095/15 Km/Hr
speed=0.001219/3 Km/Hr
speed=1219/3000000 Km/Hr
Hope this helps you.