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5a+11+3a-7=-4 What does a equal?
Combing Like terms and Isolating 'a' on one side of the equaton:
 5a+11+3a-7=-4
  8a + 4 = -4    |Isolating 'a' by perfoming ALLOWABLE operations
    8a = -8      |Subtracting 4 from 'each side' of the equaton
     a = -1      |Dividing 'each side' of the equaton by 8
CHECKING our Answer*** 
 5a+11+3a-7=-4
 -5 + 11 - 3 - 7 = -4    (substituting a= -1)