For this case we have the following expression:
 

 From here, we must clear the value of a. 
 We then have the following steps: 
 Place the terms that depend on a on the same side of the equation: 
 

 Do common factor "a": 
 

 Clear the value of "a" by dividing the factor within the parenthesis:
 

 Answer: 
 The clear expression for "a" is given by: 
 
