Original Figure:
Length = 15
Width = 5
Height = 10
Volume = Length*Width*Height
Volume = 15*5*10
Volume = 750
New Figure
Length = 3
Width = 1
Height = 2
Each dimension has been divided by 5 (eg: 15/5 = 3)
Volume = Length*Width*Height
Volume = 3*1*2
Volume = 6
The old volume was 750 and it changes to 6
Notice how 750/6 = 125
Which can be rearranged to 750/125 = 6
Answer: if you divide the old volume by 125, then you get the new volume
Note: the new volume is 125 times smaller than the old volume
Put another way, the old volume is 125 times larger compared to the new volume
The fact that 125 = 5^3 is not a coincidence. If you divide each dimension by some number k, then you divide the volume by k^3
        
             
        
        
        
For D:
A triangle always has 180 degrees total. No more, no less. Seeing as though all the sides and angles are the same length, we can just divide 180 by 3, giving us 60. x = 60 degrees. 
For E:
We can see there is a 90 degree symbol that surmises both angles. We know the lower angle is 30 degrees, so m must equal 60 degrees.
For G: 
Same concept as D, except we gotta do a bit of math. A triangle always has 180 degrees, So we add 50 and 55 together and get 105. Subtract 105 from 180 and we get 75. Therefore, your angle is 75 degrees.
For H:
The 75 degree angle and m are parallel, with the same line passing through it, meaning that m is identical to the other angle. m = 75.