Answer:
2(x+10)
Step-by-step explanation:
Well since sum is addition and the number and 10 are the sum, let’s make the “number“ (x) and add em up. 10+x. 
Now we gotta double that sum which is basically 
2(10+x)
 
        
                    
             
        
        
        
Here you have an equilateral triangle. Because of this you know that all angles are also the same as each other. We know that the angles in an equilateral triangle are 60°. 
so let's set 7x + 4 = 60
Subtract 4 from both sides: 7x = 56
Divide both sides by 7: x = 8
        
             
        
        
        
Answer:
b) 0.0625
Step-by-step explanation:
 
        
                    
             
        
        
        
Cent is by the hundred so one percent is 1/100 so .6%=6/1000
which can be reduced to 3/500
        
             
        
        
        
I did not catch well, but i think you already got your answers. Let me explain. For the first part you got your notation right: for 0.0045 the correct scientific notation is 4.5 x 10^-3. Now the second part, the answer would be the first one, the notation that you are giving is the one who corresponds to <span>4.5 x 10^-2, the first option you have. Hope it helps</span>