60 minutes. Take how far it is above ground (20 m) and add it to the absolute value of how far it is below ground (340 m) to get 360 meters, which you divide by the rate of descent (6 m/min) to get 60 minutes.
You can convert them to decimals and multiply. Remember when using decimals, it is over 10 or 100 <span />
You know that 7*7 is 49, and 6*6 is 36. Now you know it will be 6._. 6*7 is 42, so think of that as 6.5^2. You know that it will most likely be less than 6.8 since it is so close to being 7*7, which is 4 above your desired number. This leaves 6.6 to 6.8 as your estimate. Personally, I would go straight in the middle and choose 6.7.
I hope this helps!
They were 1 mile away from each other.
4-3=1 mile