2.
M must be (0,0) since it coincides with the origin
R must be (a+b, √(a²-b²)). 
The x-coordinate is b from A translated to the right by a.
The y-coordinate is the same as A.
(I think the square root is there to confuse you).
3.
R(0,0)
C(a,b) (same x as T, same Y as E)
5.
Not sure how to prove that.
        
             
        
        
        
For an estimate, the closest is 210
        
             
        
        
        
Because α varies directley to β

(k = constant)
α=7 when β=2 
7= 2k
k= 
 
 so when α=21
21= 

 b
b= 6
 
        
        
        
You know that d = 100 and w = 125, so you plug that into the equation and solve as shown:
b= 100 + d - w
  = 100 + 100 - 125
  = 200 - 125
  = $75
You now have $75 left as balance.