You have to formulate equations for this problem.
Let S = Science score
      M = Math score
       C =
Chemistry score
To illustrate the given:
0.9S = 0.75M
0.9S = 0.8C
You are given that Karen’s Math score is 96 marks. You have
to substitute the Math score to the first equation.
0.9S = 0.75(96)
0.9S = 72
S = 80
Therefore, Karen’s Science score is 80. Now, you have to
substitute the Science score to the second equation.
0.9(80) = 0.8C
0.8C = 72
C = 90
So, Karen’s Chemistry score is 90.
Therefore, the total score of the 3 subjects is 266 (96 + 80
+ 90).
 
        
             
        
        
        
Use this version of the Law of Cosines to find side b:
b^2 = a^2 + c^2 − 2ac cos(B)
We want side b.
b^2 = (41)^2 + (20)^2 - 2(41)(20)cos(36°)
After finding b, you can use the Law of Sines to find angles A and C or use other forms of the Law of Cosines to find angles A and C. 
Try it....
 
        
             
        
        
        
Answer:
1
Step-by-step explanation:
to lazy 
 
        
                    
             
        
        
        
Answer:
5*2+1/2*-2
11/2*-2
-11
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
I don't think I know it sorry