Question 390991
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Hi,         
solving by combining like terms & isolating the variable a  on one side of equation
   9 = -7 -2a +a  |combining like terms on the right side
   9 = -7 -a      | adding a to both sides of the equation
  a + 9 = -7      | subtracting 9 to both sides of the equation   
     a = -16