Your answer would be the last option, c = √(E/m). 
We can see this when we rearrange the equation, as:
E = mc²
÷ m
E/m = c²
√
√(E/m) = c
So you got all the steps in rearranging correct :)
I hope this helps!
        
             
        
        
        
Answer:(3x+7)(x+2)
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
x=20
Step-by-step explanation:
Well just cross multiply if its easier
x(3)=3x
12*5=60
60=3x
x=20
 
        
                    
             
        
        
        
Answer:
51 + 29+ 80
Step-by-step explanation:
she got this by adding 51 + 29
 
        
             
        
        
        
Answer:

Step-by-step explanation:
Let's start by factoring everything:


Now, you can cancel out some terms:

Now, when you divide a fraction by another fraction, that is the same as multiplying the first fraction by the reciprocal of the second one:


Hope this helps!