it's about and ratios and porportions

Good Afternoon, 

I will go over each one so you understand:
  
       First Question: How far can snail D travel in 1 hour?
Well, we know That snail D travels 6 inches in 30 minutes, and we also know that 30 minutes is  of an hour. Therefore, we can multiply 30 minutes by 2 to get an hour, and do the same with the amount of inches this snail travels. So 6 x 2 = 12. He travels 12 inches in an hour :)
   
      Second Question:  Here we do the same thing, except the snail travels 1 inch in 15 minutes and we want to know how much he travels in 30 minutes, so 2 x 1 = 2. The snail travels 2 inches in 30 minutes. Thats a slow snail!
   

Documentation and time management