Answer:
10
Step-by-step explanation:
Two negatives equal a positive.
 
        
                    
             
        
        
        
0.76 or 76/100. Simply add 2 zeros to 6/10 to make it 60/100. That'll make the problem alot easier :).
        
             
        
        
        
The total area of the blades is the area of a triangle multiplied by 4.
 We have then:
 
 Where,
 b: base of the blades
 h: height of the blades
 Substituting values we have:

 Doing the calculation we have that the area of the blades is given by:

 Answer:
 The total area of the blades is:
 