Answer:
See below
Step-by-step explanation:
The first one 'cubes' the denominator AND the numerator:
(-2/5)^3 = -2/5 * -2/5 * -2/5 = -8/125
The second one 'cubes' only the denominator:
-2/5^3 = -2 / (5 * 5 * 5) = - 2 / 125
Mr. Mole's burrow was at an altitude of 6 meters below the ground.
Step-by-step explanation:
Step 1:
We need to determine the distance that Mr. Mole covers in a single minute.
To do that we divide the difference in values of altitude by the difference in the time periods.
For the first case, Mr. Mole had traveled -18 meters in 5 minutes.
We also have, he traveled -25.2 meters in 8 minutes.
Step 2:
The distance he covered in 1 minute 

So with every minute, Mr. Mole digs down an additional 2.4 meters below the surface.
To determine where Mr. Mole's burrow is we subtract the distance traveled in 5 minutes from -18.
The altitude of Mr. Mole's burrow 
So Mr. Mole's burrow was at an altitude of 6 meters below the ground i.e. -6 meters.