An example should make this clear.
If  $50  is 40%   what is the value of the whole amount?
Answer:-  Whole amount = 100^%
By proportion this =  (100/ 40) * 50
= 2.5 * 50 
= $125    (answer)
 
        
             
        
        
        
Answer:
B 41.4
Step-by-step explanation:
complete Pythagoras for general triangles :
c² = a² + b² - 2ab×cos(C)
with "c" being the side opposite of the angle C.
=>
8² = 10² + 12² - 2×10×12×cos(C)
64 = 244 - 240×cos(C)
240×cos(C) = 244 - 64 = 180
cos(C) = 180/240 = 18/24 = 3/4 = 0.75
C = 41.40962211... ≈ 41.4
 
        
             
        
        
        
The answer is 80 because all triangles equal 180
        
                    
             
        
        
        
4 is the proportion because 8 + 4 is 12 then keep adding 12 + 4 = 16 + 4 = 20 So that mean it is proportional I hope that helps.